diff --git a/cameraserver/src/main/native/cpp/cameraserver/CameraServer.cpp b/cameraserver/src/main/native/cpp/cameraserver/CameraServer.cpp
index 19de47b9d0..5f068a15e1 100644
--- a/cameraserver/src/main/native/cpp/cameraserver/CameraServer.cpp
+++ b/cameraserver/src/main/native/cpp/cameraserver/CameraServer.cpp
@@ -529,7 +529,7 @@ cs::AxisCamera CameraServer::AddAxisCamera(const std::string& host) {
   return AddAxisCamera("Axis Camera", host);
 }
 
-cs::AxisCamera CameraServer::AddAxisCamera(wpi::ArrayRef<std::string> hosts) {
+cs::AxisCamera CameraServer::AddAxisCamera(wpi::span<const std::string> hosts) {
   return AddAxisCamera("Axis Camera", hosts);
 }
 
@@ -561,7 +561,7 @@ cs::AxisCamera CameraServer::AddAxisCamera(std::string_view name,
 }
 
 cs::AxisCamera CameraServer::AddAxisCamera(std::string_view name,
-                                           wpi::ArrayRef<std::string> hosts) {
+                                           wpi::span<const std::string> hosts) {
   cs::AxisCamera camera{name, hosts};
   StartAutomaticCapture(camera);
   auto csShared = GetCameraServerShared();
diff --git a/cameraserver/src/main/native/include/cameraserver/CameraServer.h b/cameraserver/src/main/native/include/cameraserver/CameraServer.h
index e5ce45766f..ac304fbadc 100644
--- a/cameraserver/src/main/native/include/cameraserver/CameraServer.h
+++ b/cameraserver/src/main/native/include/cameraserver/CameraServer.h
@@ -10,7 +10,7 @@
 #include <string>
 #include <string_view>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "cscore.h"
 #include "cscore_cv.h"
@@ -116,7 +116,7 @@ class CameraServer {
    *
    * @param hosts Array of Camera host IPs/DNS names
    */
-  cs::AxisCamera AddAxisCamera(wpi::ArrayRef<std::string> hosts);
+  cs::AxisCamera AddAxisCamera(wpi::span<const std::string> hosts);
 
   /**
    * Adds an Axis IP camera.
@@ -159,7 +159,7 @@ class CameraServer {
    * @param hosts Array of Camera host IPs/DNS names
    */
   cs::AxisCamera AddAxisCamera(std::string_view name,
-                               wpi::ArrayRef<std::string> hosts);
+                               wpi::span<const std::string> hosts);
 
   /**
    * Adds an Axis IP camera.
diff --git a/cscore/src/main/native/cpp/ConfigurableSourceImpl.cpp b/cscore/src/main/native/cpp/ConfigurableSourceImpl.cpp
index 78cd988640..16452f1c74 100644
--- a/cscore/src/main/native/cpp/ConfigurableSourceImpl.cpp
+++ b/cscore/src/main/native/cpp/ConfigurableSourceImpl.cpp
@@ -88,7 +88,7 @@ int ConfigurableSourceImpl::CreateProperty(
 }
 
 void ConfigurableSourceImpl::SetEnumPropertyChoices(
-    int property, wpi::ArrayRef<std::string> choices, CS_Status* status) {
+    int property, wpi::span<const std::string> choices, CS_Status* status) {
   std::scoped_lock lock(m_mutex);
   auto prop = GetProperty(property);
   if (!prop) {
@@ -99,7 +99,7 @@ void ConfigurableSourceImpl::SetEnumPropertyChoices(
     *status = CS_WRONG_PROPERTY_TYPE;
     return;
   }
-  prop->enumChoices = choices;
+  prop->enumChoices.assign(choices.begin(), choices.end());
   m_notifier.NotifySourceProperty(*this, CS_SOURCE_PROPERTY_CHOICES_UPDATED,
                                   prop->name, property, CS_PROP_ENUM,
                                   prop->value, {});
diff --git a/cscore/src/main/native/cpp/ConfigurableSourceImpl.h b/cscore/src/main/native/cpp/ConfigurableSourceImpl.h
index bfc07f903e..bb9f3ed70f 100644
--- a/cscore/src/main/native/cpp/ConfigurableSourceImpl.h
+++ b/cscore/src/main/native/cpp/ConfigurableSourceImpl.h
@@ -12,7 +12,7 @@
 #include <string_view>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "SourceImpl.h"
 
@@ -41,7 +41,8 @@ class ConfigurableSourceImpl : public SourceImpl {
   int CreateProperty(std::string_view name, CS_PropertyKind kind, int minimum,
                      int maximum, int step, int defaultValue, int value,
                      std::function<void(CS_Property property)> onChange);
-  void SetEnumPropertyChoices(int property, wpi::ArrayRef<std::string> choices,
+  void SetEnumPropertyChoices(int property,
+                              wpi::span<const std::string> choices,
                               CS_Status* status);
 
  private:
diff --git a/cscore/src/main/native/cpp/CvSourceImpl.cpp b/cscore/src/main/native/cpp/CvSourceImpl.cpp
index d05d89af70..8d5a38d8d1 100644
--- a/cscore/src/main/native/cpp/CvSourceImpl.cpp
+++ b/cscore/src/main/native/cpp/CvSourceImpl.cpp
@@ -140,7 +140,7 @@ CS_Property CreateSourcePropertyCallback(
 }
 
 void SetSourceEnumPropertyChoices(CS_Source source, CS_Property property,
-                                  wpi::ArrayRef<std::string> choices,
+                                  wpi::span<const std::string> choices,
                                   CS_Status* status) {
   auto data = Instance::GetInstance().GetSource(source);
   if (!data || (data->kind & SourceMask) == 0) {
diff --git a/cscore/src/main/native/cpp/CvSourceImpl.h b/cscore/src/main/native/cpp/CvSourceImpl.h
index 1956fbe56d..fba7131b43 100644
--- a/cscore/src/main/native/cpp/CvSourceImpl.h
+++ b/cscore/src/main/native/cpp/CvSourceImpl.h
@@ -13,7 +13,6 @@
 #include <vector>
 
 #include <opencv2/core/core.hpp>
-#include <wpi/ArrayRef.h>
 
 #include "ConfigurableSourceImpl.h"
 #include "SourceImpl.h"
diff --git a/cscore/src/main/native/cpp/HttpCameraImpl.cpp b/cscore/src/main/native/cpp/HttpCameraImpl.cpp
index 5cbe9436d6..068393b88f 100644
--- a/cscore/src/main/native/cpp/HttpCameraImpl.cpp
+++ b/cscore/src/main/native/cpp/HttpCameraImpl.cpp
@@ -378,7 +378,7 @@ CS_HttpCameraKind HttpCameraImpl::GetKind() const {
   return m_kind;
 }
 
-bool HttpCameraImpl::SetUrls(wpi::ArrayRef<std::string> urls,
+bool HttpCameraImpl::SetUrls(wpi::span<const std::string> urls,
                              CS_Status* status) {
   std::vector<wpi::HttpLocation> locations;
   for (const auto& url : urls) {
@@ -571,14 +571,15 @@ CS_Source CreateHttpCamera(std::string_view name, std::string_view url,
                                                 inst.notifier, inst.telemetry);
       break;
   }
-  if (!source->SetUrls(std::string{url}, status)) {
+  std::string urlStr{url};
+  if (!source->SetUrls(wpi::span{&urlStr, 1}, status)) {
     return 0;
   }
   return inst.CreateSource(CS_SOURCE_HTTP, source);
 }
 
 CS_Source CreateHttpCamera(std::string_view name,
-                           wpi::ArrayRef<std::string> urls,
+                           wpi::span<const std::string> urls,
                            CS_HttpCameraKind kind, CS_Status* status) {
   auto& inst = Instance::GetInstance();
   if (urls.empty()) {
@@ -602,7 +603,7 @@ CS_HttpCameraKind GetHttpCameraKind(CS_Source source, CS_Status* status) {
   return static_cast<HttpCameraImpl&>(*data->source).GetKind();
 }
 
-void SetHttpCameraUrls(CS_Source source, wpi::ArrayRef<std::string> urls,
+void SetHttpCameraUrls(CS_Source source, wpi::span<const std::string> urls,
                        CS_Status* status) {
   if (urls.empty()) {
     *status = CS_EMPTY_VALUE;
diff --git a/cscore/src/main/native/cpp/HttpCameraImpl.h b/cscore/src/main/native/cpp/HttpCameraImpl.h
index 1d375a82df..2c589362e2 100644
--- a/cscore/src/main/native/cpp/HttpCameraImpl.h
+++ b/cscore/src/main/native/cpp/HttpCameraImpl.h
@@ -19,6 +19,7 @@
 #include <wpi/StringMap.h>
 #include <wpi/condition_variable.h>
 #include <wpi/raw_istream.h>
+#include <wpi/span.h>
 
 #include "SourceImpl.h"
 #include "cscore_cpp.h"
@@ -54,7 +55,7 @@ class HttpCameraImpl : public SourceImpl {
   void NumSinksEnabledChanged() override;
 
   CS_HttpCameraKind GetKind() const;
-  bool SetUrls(wpi::ArrayRef<std::string> urls, CS_Status* status);
+  bool SetUrls(wpi::span<const std::string> urls, CS_Status* status);
   std::vector<std::string> GetUrls() const;
 
   // Property data
diff --git a/cscore/src/main/native/cpp/Instance.h b/cscore/src/main/native/cpp/Instance.h
index fba616353e..f84eacf4d0 100644
--- a/cscore/src/main/native/cpp/Instance.h
+++ b/cscore/src/main/native/cpp/Instance.h
@@ -86,18 +86,17 @@ class Instance {
   void DestroySource(CS_Source handle);
   void DestroySink(CS_Sink handle);
 
-  wpi::ArrayRef<CS_Source> EnumerateSourceHandles(
+  wpi::span<CS_Source> EnumerateSourceHandles(
       wpi::SmallVectorImpl<CS_Source>& vec) {
     return m_sources.GetAll(vec);
   }
 
-  wpi::ArrayRef<CS_Sink> EnumerateSinkHandles(
-      wpi::SmallVectorImpl<CS_Sink>& vec) {
+  wpi::span<CS_Sink> EnumerateSinkHandles(wpi::SmallVectorImpl<CS_Sink>& vec) {
     return m_sinks.GetAll(vec);
   }
 
-  wpi::ArrayRef<CS_Sink> EnumerateSourceSinks(
-      CS_Source source, wpi::SmallVectorImpl<CS_Sink>& vec) {
+  wpi::span<CS_Sink> EnumerateSourceSinks(CS_Source source,
+                                          wpi::SmallVectorImpl<CS_Sink>& vec) {
     vec.clear();
     m_sinks.ForEach([&](CS_Sink sinkHandle, const SinkData& data) {
       if (source == data.sourceHandle.load()) {
diff --git a/cscore/src/main/native/cpp/PropertyContainer.cpp b/cscore/src/main/native/cpp/PropertyContainer.cpp
index d95c06edfa..b1d3a6f793 100644
--- a/cscore/src/main/native/cpp/PropertyContainer.cpp
+++ b/cscore/src/main/native/cpp/PropertyContainer.cpp
@@ -27,7 +27,7 @@ int PropertyContainer::GetPropertyIndex(std::string_view name) const {
   return ndx;
 }
 
-wpi::ArrayRef<int> PropertyContainer::EnumerateProperties(
+wpi::span<int> PropertyContainer::EnumerateProperties(
     wpi::SmallVectorImpl<int>& vec, CS_Status* status) const {
   if (!m_properties_cached && !CacheProperties(status)) {
     return {};
diff --git a/cscore/src/main/native/cpp/PropertyContainer.h b/cscore/src/main/native/cpp/PropertyContainer.h
index f09ea23c7b..a00c675248 100644
--- a/cscore/src/main/native/cpp/PropertyContainer.h
+++ b/cscore/src/main/native/cpp/PropertyContainer.h
@@ -12,9 +12,9 @@
 #include <string_view>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
 #include <wpi/StringMap.h>
 #include <wpi/mutex.h>
+#include <wpi/span.h>
 
 #include "PropertyImpl.h"
 #include "cscore_cpp.h"
@@ -33,8 +33,8 @@ class PropertyContainer {
   virtual ~PropertyContainer() = default;
 
   int GetPropertyIndex(std::string_view name) const;
-  wpi::ArrayRef<int> EnumerateProperties(wpi::SmallVectorImpl<int>& vec,
-                                         CS_Status* status) const;
+  wpi::span<int> EnumerateProperties(wpi::SmallVectorImpl<int>& vec,
+                                     CS_Status* status) const;
   CS_PropertyKind GetPropertyKind(int property) const;
   std::string_view GetPropertyName(int property,
                                    wpi::SmallVectorImpl<char>& buf,
diff --git a/cscore/src/main/native/cpp/RawSourceImpl.h b/cscore/src/main/native/cpp/RawSourceImpl.h
index bb9a49fc67..5887ed4203 100644
--- a/cscore/src/main/native/cpp/RawSourceImpl.h
+++ b/cscore/src/main/native/cpp/RawSourceImpl.h
@@ -12,8 +12,6 @@
 #include <string_view>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
-
 #include "ConfigurableSourceImpl.h"
 #include "SourceImpl.h"
 #include "cscore_raw.h"
diff --git a/cscore/src/main/native/cpp/SourceImpl.h b/cscore/src/main/native/cpp/SourceImpl.h
index 0a7839e23a..dd2e574f19 100644
--- a/cscore/src/main/native/cpp/SourceImpl.h
+++ b/cscore/src/main/native/cpp/SourceImpl.h
@@ -12,7 +12,6 @@
 #include <string_view>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
 #include <wpi/Logger.h>
 #include <wpi/condition_variable.h>
 #include <wpi/mutex.h>
diff --git a/cscore/src/main/native/cpp/UnlimitedHandleResource.h b/cscore/src/main/native/cpp/UnlimitedHandleResource.h
index cba6399b53..f7671ae4f5 100644
--- a/cscore/src/main/native/cpp/UnlimitedHandleResource.h
+++ b/cscore/src/main/native/cpp/UnlimitedHandleResource.h
@@ -9,9 +9,9 @@
 #include <utility>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallVector.h>
 #include <wpi/mutex.h>
+#include <wpi/span.h>
 
 namespace cs {
 
@@ -50,7 +50,7 @@ class UnlimitedHandleResource {
   std::shared_ptr<TStruct> Free(THandle handle);
 
   template <typename T>
-  wpi::ArrayRef<T> GetAll(wpi::SmallVectorImpl<T>& vec);
+  wpi::span<T> GetAll(wpi::SmallVectorImpl<T>& vec);
 
   std::vector<std::shared_ptr<TStruct>> FreeAll();
 
@@ -151,7 +151,7 @@ UnlimitedHandleResource<THandle, TStruct, typeValue, TMutex>::Free(
 
 template <typename THandle, typename TStruct, int typeValue, typename TMutex>
 template <typename T>
-inline wpi::ArrayRef<T>
+inline wpi::span<T>
 UnlimitedHandleResource<THandle, TStruct, typeValue, TMutex>::GetAll(
     wpi::SmallVectorImpl<T>& vec) {
   ForEach([&](THandle handle, const TStruct& data) { vec.push_back(handle); });
diff --git a/cscore/src/main/native/cpp/cscore_cpp.cpp b/cscore/src/main/native/cpp/cscore_cpp.cpp
index 7d3828e318..4faae795ed 100644
--- a/cscore/src/main/native/cpp/cscore_cpp.cpp
+++ b/cscore/src/main/native/cpp/cscore_cpp.cpp
@@ -286,13 +286,13 @@ CS_Property GetSourceProperty(CS_Source source, std::string_view name,
   return Handle{source, property, Handle::kProperty};
 }
 
-wpi::ArrayRef<CS_Property> EnumerateSourceProperties(
+wpi::span<CS_Property> EnumerateSourceProperties(
     CS_Source source, wpi::SmallVectorImpl<CS_Property>& vec,
     CS_Status* status) {
   auto data = Instance::GetInstance().GetSource(source);
   if (!data) {
     *status = CS_INVALID_HANDLE;
-    return 0;
+    return {};
   }
   wpi::SmallVector<int, 32> properties_buf;
   for (auto property :
@@ -398,14 +398,14 @@ std::vector<VideoMode> EnumerateSourceVideoModes(CS_Source source,
   return data->source->EnumerateVideoModes(status);
 }
 
-wpi::ArrayRef<CS_Sink> EnumerateSourceSinks(CS_Source source,
-                                            wpi::SmallVectorImpl<CS_Sink>& vec,
-                                            CS_Status* status) {
+wpi::span<CS_Sink> EnumerateSourceSinks(CS_Source source,
+                                        wpi::SmallVectorImpl<CS_Sink>& vec,
+                                        CS_Status* status) {
   auto& inst = Instance::GetInstance();
   auto data = inst.GetSource(source);
   if (!data) {
     *status = CS_INVALID_HANDLE;
-    return wpi::ArrayRef<CS_Sink>{};
+    return {};
   }
   return inst.EnumerateSourceSinks(source, vec);
 }
@@ -583,12 +583,12 @@ CS_Property GetSinkProperty(CS_Sink sink, std::string_view name,
   return Handle{sink, property, Handle::kSinkProperty};
 }
 
-wpi::ArrayRef<CS_Property> EnumerateSinkProperties(
+wpi::span<CS_Property> EnumerateSinkProperties(
     CS_Sink sink, wpi::SmallVectorImpl<CS_Property>& vec, CS_Status* status) {
   auto data = Instance::GetInstance().GetSink(sink);
   if (!data) {
     *status = CS_INVALID_HANDLE;
-    return 0;
+    return {};
   }
   wpi::SmallVector<int, 32> properties_buf;
   for (auto property :
@@ -861,13 +861,13 @@ void Shutdown() {
 // Utility Functions
 //
 
-wpi::ArrayRef<CS_Source> EnumerateSourceHandles(
+wpi::span<CS_Source> EnumerateSourceHandles(
     wpi::SmallVectorImpl<CS_Source>& vec, CS_Status* status) {
   return Instance::GetInstance().EnumerateSourceHandles(vec);
 }
 
-wpi::ArrayRef<CS_Sink> EnumerateSinkHandles(wpi::SmallVectorImpl<CS_Sink>& vec,
-                                            CS_Status* status) {
+wpi::span<CS_Sink> EnumerateSinkHandles(wpi::SmallVectorImpl<CS_Sink>& vec,
+                                        CS_Status* status) {
   return Instance::GetInstance().EnumerateSinkHandles(vec);
 }
 
diff --git a/cscore/src/main/native/cpp/jni/CameraServerJNI.cpp b/cscore/src/main/native/cpp/jni/CameraServerJNI.cpp
index afdf566787..8b648f8b14 100644
--- a/cscore/src/main/native/cpp/jni/CameraServerJNI.cpp
+++ b/cscore/src/main/native/cpp/jni/CameraServerJNI.cpp
@@ -8,6 +8,7 @@
 #include <opencv2/core/core.hpp>
 #include <wpi/SmallString.h>
 #include <wpi/jni_util.h>
+#include <wpi/span.h>
 
 #include "cscore_cpp.h"
 #include "cscore_cv.h"
@@ -294,7 +295,8 @@ static jobject MakeJObject(JNIEnv* env, const cs::RawEvent& event) {
   // clang-format on
 }
 
-static jobjectArray MakeJObject(JNIEnv* env, wpi::ArrayRef<cs::RawEvent> arr) {
+static jobjectArray MakeJObject(JNIEnv* env,
+                                wpi::span<const cs::RawEvent> arr) {
   jobjectArray jarr = env->NewObjectArray(arr.size(), videoEventCls, nullptr);
   if (!jarr) {
     return nullptr;
diff --git a/cscore/src/main/native/include/cscore_cpp.h b/cscore/src/main/native/include/cscore_cpp.h
index 593ad08936..8b1eab1788 100644
--- a/cscore/src/main/native/include/cscore_cpp.h
+++ b/cscore/src/main/native/include/cscore_cpp.h
@@ -12,8 +12,8 @@
 #include <string_view>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallVector.h>
+#include <wpi/span.h>
 
 #include "cscore_c.h"
 
@@ -203,7 +203,7 @@ CS_Source CreateUsbCameraPath(std::string_view name, std::string_view path,
 CS_Source CreateHttpCamera(std::string_view name, std::string_view url,
                            CS_HttpCameraKind kind, CS_Status* status);
 CS_Source CreateHttpCamera(std::string_view name,
-                           wpi::ArrayRef<std::string> urls,
+                           wpi::span<const std::string> urls,
                            CS_HttpCameraKind kind, CS_Status* status);
 CS_Source CreateCvSource(std::string_view name, const VideoMode& mode,
                          CS_Status* status);
@@ -230,7 +230,7 @@ bool IsSourceConnected(CS_Source source, CS_Status* status);
 bool IsSourceEnabled(CS_Source source, CS_Status* status);
 CS_Property GetSourceProperty(CS_Source source, std::string_view name,
                               CS_Status* status);
-wpi::ArrayRef<CS_Property> EnumerateSourceProperties(
+wpi::span<CS_Property> EnumerateSourceProperties(
     CS_Source source, wpi::SmallVectorImpl<CS_Property>& vec,
     CS_Status* status);
 VideoMode GetSourceVideoMode(CS_Source source, CS_Status* status);
@@ -249,9 +249,9 @@ std::string GetSourceConfigJson(CS_Source source, CS_Status* status);
 wpi::json GetSourceConfigJsonObject(CS_Source source, CS_Status* status);
 std::vector<VideoMode> EnumerateSourceVideoModes(CS_Source source,
                                                  CS_Status* status);
-wpi::ArrayRef<CS_Sink> EnumerateSourceSinks(CS_Source source,
-                                            wpi::SmallVectorImpl<CS_Sink>& vec,
-                                            CS_Status* status);
+wpi::span<CS_Sink> EnumerateSourceSinks(CS_Source source,
+                                        wpi::SmallVectorImpl<CS_Sink>& vec,
+                                        CS_Status* status);
 CS_Source CopySource(CS_Source source, CS_Status* status);
 void ReleaseSource(CS_Source source, CS_Status* status);
 /** @} */
@@ -285,7 +285,7 @@ UsbCameraInfo GetUsbCameraInfo(CS_Source source, CS_Status* status);
  * @{
  */
 CS_HttpCameraKind GetHttpCameraKind(CS_Source source, CS_Status* status);
-void SetHttpCameraUrls(CS_Source source, wpi::ArrayRef<std::string> urls,
+void SetHttpCameraUrls(CS_Source source, wpi::span<const std::string> urls,
                        CS_Status* status);
 std::vector<std::string> GetHttpCameraUrls(CS_Source source, CS_Status* status);
 /** @} */
@@ -304,7 +304,7 @@ CS_Property CreateSourceProperty(CS_Source source, std::string_view name,
                                  int step, int defaultValue, int value,
                                  CS_Status* status);
 void SetSourceEnumPropertyChoices(CS_Source source, CS_Property property,
-                                  wpi::ArrayRef<std::string> choices,
+                                  wpi::span<const std::string> choices,
                                   CS_Status* status);
 /** @} */
 
@@ -335,7 +335,7 @@ std::string_view GetSinkDescription(CS_Sink sink,
                                     CS_Status* status);
 CS_Property GetSinkProperty(CS_Sink sink, std::string_view name,
                             CS_Status* status);
-wpi::ArrayRef<CS_Property> EnumerateSinkProperties(
+wpi::span<CS_Property> EnumerateSinkProperties(
     CS_Sink sink, wpi::SmallVectorImpl<CS_Property>& vec, CS_Status* status);
 void SetSinkSource(CS_Sink sink, CS_Source source, CS_Status* status);
 CS_Property GetSinkSourceProperty(CS_Sink sink, std::string_view name,
@@ -430,10 +430,10 @@ void Shutdown();
  */
 std::vector<UsbCameraInfo> EnumerateUsbCameras(CS_Status* status);
 
-wpi::ArrayRef<CS_Source> EnumerateSourceHandles(
+wpi::span<CS_Source> EnumerateSourceHandles(
     wpi::SmallVectorImpl<CS_Source>& vec, CS_Status* status);
-wpi::ArrayRef<CS_Sink> EnumerateSinkHandles(wpi::SmallVectorImpl<CS_Sink>& vec,
-                                            CS_Status* status);
+wpi::span<CS_Sink> EnumerateSinkHandles(wpi::SmallVectorImpl<CS_Sink>& vec,
+                                        CS_Status* status);
 
 std::string GetHostname();
 
diff --git a/cscore/src/main/native/include/cscore_oo.h b/cscore/src/main/native/include/cscore_oo.h
index 384d5230b2..f780fcd003 100644
--- a/cscore/src/main/native/include/cscore_oo.h
+++ b/cscore/src/main/native/include/cscore_oo.h
@@ -11,6 +11,8 @@
 #include <utility>
 #include <vector>
 
+#include <wpi/span.h>
+
 #include "cscore_cpp.h"
 
 namespace cs {
@@ -514,7 +516,7 @@ class HttpCamera : public VideoCamera {
    * @param urls Array of Camera URLs
    * @param kind Camera kind (e.g. kAxis)
    */
-  HttpCamera(std::string_view name, wpi::ArrayRef<std::string> urls,
+  HttpCamera(std::string_view name, wpi::span<const std::string> urls,
              HttpCameraKind kind = kUnknown);
 
   /**
@@ -539,7 +541,7 @@ class HttpCamera : public VideoCamera {
   /**
    * Change the URLs used to connect to the camera.
    */
-  void SetUrls(wpi::ArrayRef<std::string> urls);
+  void SetUrls(wpi::span<const std::string> urls);
 
   /**
    * Change the URLs used to connect to the camera.
@@ -558,7 +560,7 @@ class HttpCamera : public VideoCamera {
  */
 class AxisCamera : public HttpCamera {
   static std::string HostToUrl(std::string_view host);
-  static std::vector<std::string> HostToUrl(wpi::ArrayRef<std::string> hosts);
+  static std::vector<std::string> HostToUrl(wpi::span<const std::string> hosts);
   template <typename T>
   static std::vector<std::string> HostToUrl(std::initializer_list<T> hosts);
 
@@ -597,7 +599,7 @@ class AxisCamera : public HttpCamera {
    * @param hosts Array of Camera host IPs/DNS names
    * @param kind Camera kind (e.g. kAxis)
    */
-  AxisCamera(std::string_view name, wpi::ArrayRef<std::string> hosts);
+  AxisCamera(std::string_view name, wpi::span<const std::string> hosts);
 
   /**
    * Create a source for an Axis IP camera.
@@ -698,7 +700,7 @@ class ImageSource : public VideoSource {
    * @param choices Choices
    */
   void SetEnumPropertyChoices(const VideoProperty& property,
-                              wpi::ArrayRef<std::string> choices);
+                              wpi::span<const std::string> choices);
 
   /**
    * Configure enum property choices.
diff --git a/cscore/src/main/native/include/cscore_oo.inc b/cscore/src/main/native/include/cscore_oo.inc
index 878462afdb..5037d97982 100644
--- a/cscore/src/main/native/include/cscore_oo.inc
+++ b/cscore/src/main/native/include/cscore_oo.inc
@@ -302,7 +302,7 @@ inline HttpCamera::HttpCamera(std::string_view name, const std::string& url,
     : HttpCamera(name, std::string_view{url}, kind) {}
 
 inline HttpCamera::HttpCamera(std::string_view name,
-                              wpi::ArrayRef<std::string> urls,
+                              wpi::span<const std::string> urls,
                               HttpCameraKind kind) {
   m_handle = CreateHttpCamera(
       name, urls, static_cast<CS_HttpCameraKind>(static_cast<int>(kind)),
@@ -329,7 +329,7 @@ inline HttpCamera::HttpCameraKind HttpCamera::GetHttpCameraKind() const {
       static_cast<int>(::cs::GetHttpCameraKind(m_handle, &m_status)));
 }
 
-inline void HttpCamera::SetUrls(wpi::ArrayRef<std::string> urls) {
+inline void HttpCamera::SetUrls(wpi::span<const std::string> urls) {
   m_status = 0;
   ::cs::SetHttpCameraUrls(m_handle, urls, &m_status);
 }
@@ -351,7 +351,7 @@ inline std::vector<std::string> HttpCamera::GetUrls() const {
 }
 
 inline std::vector<std::string> AxisCamera::HostToUrl(
-    wpi::ArrayRef<std::string> hosts) {
+    wpi::span<const std::string> hosts) {
   std::vector<std::string> rv;
   rv.reserve(hosts.size());
   for (const auto& host : hosts) {
@@ -381,7 +381,7 @@ inline AxisCamera::AxisCamera(std::string_view name, const std::string& host)
     : HttpCamera(name, HostToUrl(std::string_view{host}), kAxis) {}
 
 inline AxisCamera::AxisCamera(std::string_view name,
-                              wpi::ArrayRef<std::string> hosts)
+                              wpi::span<const std::string> hosts)
     : HttpCamera(name, HostToUrl(hosts), kAxis) {}
 
 template <typename T>
@@ -452,7 +452,7 @@ inline VideoProperty ImageSource::CreateStringProperty(std::string_view name,
 }
 
 inline void ImageSource::SetEnumPropertyChoices(
-    const VideoProperty& property, wpi::ArrayRef<std::string> choices) {
+    const VideoProperty& property, wpi::span<const std::string> choices) {
   m_status = 0;
   SetSourceEnumPropertyChoices(m_handle, property.m_handle, choices, &m_status);
 }
diff --git a/glass/src/lib/native/cpp/other/Field2D.cpp b/glass/src/lib/native/cpp/other/Field2D.cpp
index e926019674..786d3de45b 100644
--- a/glass/src/lib/native/cpp/other/Field2D.cpp
+++ b/glass/src/lib/native/cpp/other/Field2D.cpp
@@ -90,7 +90,7 @@ class PopupState {
 
   SelectedTargetInfo* GetTarget() { return &m_target; }
   FieldObjectModel* GetInsertModel() { return m_insertModel; }
-  wpi::ArrayRef<frc::Pose2d> GetInsertPoses() const { return m_insertPoses; }
+  wpi::span<const frc::Pose2d> GetInsertPoses() const { return m_insertPoses; }
 
   void Display(Field2DModel* model, const FieldFrameData& ffd);
 
@@ -184,7 +184,7 @@ class ObjectInfo {
 
   DisplayOptions GetDisplayOptions() const;
   void DisplaySettings();
-  void DrawLine(ImDrawList* drawList, wpi::ArrayRef<ImVec2> points) const;
+  void DrawLine(ImDrawList* drawList, wpi::span<const ImVec2> points) const;
 
   void LoadImage();
   const gui::Texture& GetTexture() const { return m_texture; }
@@ -623,7 +623,7 @@ void ObjectInfo::DisplaySettings() {
 }
 
 void ObjectInfo::DrawLine(ImDrawList* drawList,
-                          wpi::ArrayRef<ImVec2> points) const {
+                          wpi::span<const ImVec2> points) const {
   if (points.empty()) {
     return;
   }
@@ -1038,9 +1038,9 @@ void FieldDisplay::DisplayObject(FieldObjectModel& model,
 
   m_drawSplit.Split(m_drawList, 2);
   m_drawSplit.SetCurrentChannel(m_drawList, 1);
-  wpi::ArrayRef<frc::Pose2d> poses = gPopupState.GetInsertModel() == &model
-                                         ? gPopupState.GetInsertPoses()
-                                         : model.GetPoses();
+  auto poses = gPopupState.GetInsertModel() == &model
+                   ? gPopupState.GetInsertPoses()
+                   : model.GetPoses();
   size_t i = 0;
   for (auto&& pose : poses) {
     PoseFrameData pfd{pose, model, i, m_ffd, displayOptions};
@@ -1113,7 +1113,8 @@ void PopupState::DisplayTarget(Field2DModel* model, const FieldFrameData& ffd) {
     m_target.objModel->SetPose(m_target.index, pose);
   }
   if (ImGui::Button("Delete Pose")) {
-    std::vector<frc::Pose2d> poses = m_target.objModel->GetPoses();
+    auto posesRef = m_target.objModel->GetPoses();
+    std::vector<frc::Pose2d> poses{posesRef.begin(), posesRef.end()};
     if (m_target.index < poses.size()) {
       poses.erase(poses.begin() + m_target.index);
       m_target.objModel->SetPoses(poses);
@@ -1150,7 +1151,8 @@ void PopupState::DisplayInsert(Field2DModel* model) {
       if (ImGui::Selectable(name.data(), selected)) {
         m_insertModel = &objModel;
         auto pose = m_insertPoses[m_insertIndex];
-        m_insertPoses = objModel.GetPoses();
+        auto posesRef = objModel.GetPoses();
+        m_insertPoses.assign(posesRef.begin(), posesRef.end());
         m_insertPoses.emplace_back(std::move(pose));
         m_insertName = name;
         m_insertIndex = m_insertPoses.size() - 1;
diff --git a/glass/src/lib/native/include/glass/hardware/LEDDisplay.h b/glass/src/lib/native/include/glass/hardware/LEDDisplay.h
index f6122080a1..c7af045897 100644
--- a/glass/src/lib/native/include/glass/hardware/LEDDisplay.h
+++ b/glass/src/lib/native/include/glass/hardware/LEDDisplay.h
@@ -4,8 +4,8 @@
 
 #pragma once
 
-#include <wpi/ArrayRef.h>
 #include <wpi/STLExtras.h>
+#include <wpi/span.h>
 
 #include "glass/Model.h"
 
@@ -27,7 +27,7 @@ class LEDDisplayModel : public glass::Model {
 
   virtual bool IsRunning() = 0;
 
-  virtual wpi::ArrayRef<Data> GetData(wpi::SmallVectorImpl<Data>& buf) = 0;
+  virtual wpi::span<const Data> GetData(wpi::SmallVectorImpl<Data>& buf) = 0;
 };
 
 class LEDDisplaysModel : public glass::Model {
diff --git a/glass/src/lib/native/include/glass/other/Field2D.h b/glass/src/lib/native/include/glass/other/Field2D.h
index c9944deff3..8c86acd702 100644
--- a/glass/src/lib/native/include/glass/other/Field2D.h
+++ b/glass/src/lib/native/include/glass/other/Field2D.h
@@ -10,8 +10,8 @@
 #include <frc/geometry/Rotation2d.h>
 #include <frc/geometry/Translation2d.h>
 #include <imgui.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/STLExtras.h>
+#include <wpi/span.h>
 
 #include "glass/Model.h"
 #include "glass/View.h"
@@ -22,8 +22,8 @@ class FieldObjectModel : public Model {
  public:
   virtual const char* GetName() const = 0;
 
-  virtual wpi::ArrayRef<frc::Pose2d> GetPoses() = 0;
-  virtual void SetPoses(wpi::ArrayRef<frc::Pose2d> poses) = 0;
+  virtual wpi::span<const frc::Pose2d> GetPoses() = 0;
+  virtual void SetPoses(wpi::span<const frc::Pose2d> poses) = 0;
   virtual void SetPose(size_t i, frc::Pose2d pose) = 0;
   virtual void SetPosition(size_t i, frc::Translation2d pos) = 0;
   virtual void SetRotation(size_t i, frc::Rotation2d rot) = 0;
diff --git a/glass/src/lib/native/include/glass/other/StringChooser.h b/glass/src/lib/native/include/glass/other/StringChooser.h
index 692eb7ca43..77f9ac2b2d 100644
--- a/glass/src/lib/native/include/glass/other/StringChooser.h
+++ b/glass/src/lib/native/include/glass/other/StringChooser.h
@@ -8,7 +8,7 @@
 #include <string_view>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "glass/Model.h"
 
@@ -24,7 +24,7 @@ class StringChooserModel : public Model {
   virtual void SetDefault(std::string_view val) = 0;
   virtual void SetSelected(std::string_view val) = 0;
   virtual void SetActive(std::string_view val) = 0;
-  virtual void SetOptions(wpi::ArrayRef<std::string> val) = 0;
+  virtual void SetOptions(wpi::span<const std::string> val) = 0;
 };
 
 void DisplayStringChooser(StringChooserModel* model);
diff --git a/glass/src/libnt/native/cpp/NTCommandScheduler.cpp b/glass/src/libnt/native/cpp/NTCommandScheduler.cpp
index 4d4e39394e..ccc64127be 100644
--- a/glass/src/libnt/native/cpp/NTCommandScheduler.cpp
+++ b/glass/src/libnt/native/cpp/NTCommandScheduler.cpp
@@ -41,11 +41,13 @@ void NTCommandSchedulerModel::Update() {
       }
     } else if (event.entry == m_commands) {
       if (event.value && event.value->IsStringArray()) {
-        m_commandsValue = event.value->GetStringArray();
+        auto arr = event.value->GetStringArray();
+        m_commandsValue.assign(arr.begin(), arr.end());
       }
     } else if (event.entry == m_ids) {
       if (event.value && event.value->IsDoubleArray()) {
-        m_idsValue = event.value->GetDoubleArray();
+        auto arr = event.value->GetDoubleArray();
+        m_idsValue.assign(arr.begin(), arr.end());
       }
     }
   }
diff --git a/glass/src/libnt/native/cpp/NTFMS.cpp b/glass/src/libnt/native/cpp/NTFMS.cpp
index 1f54803fc7..84c1ce78cc 100644
--- a/glass/src/libnt/native/cpp/NTFMS.cpp
+++ b/glass/src/libnt/native/cpp/NTFMS.cpp
@@ -7,6 +7,7 @@
 #include <stdint.h>
 
 #include <fmt/format.h>
+#include <wpi/SmallVector.h>
 #include <wpi/timestamp.h>
 
 using namespace glass;
diff --git a/glass/src/libnt/native/cpp/NTField2D.cpp b/glass/src/libnt/native/cpp/NTField2D.cpp
index 5c0c9542f5..3ce4580184 100644
--- a/glass/src/libnt/native/cpp/NTField2D.cpp
+++ b/glass/src/libnt/native/cpp/NTField2D.cpp
@@ -34,8 +34,8 @@ class NTField2DModel::ObjectModel : public FieldObjectModel {
   bool Exists() override { return nt::GetEntryType(m_entry) != NT_UNASSIGNED; }
   bool IsReadOnly() override { return false; }
 
-  wpi::ArrayRef<frc::Pose2d> GetPoses() override { return m_poses; }
-  void SetPoses(wpi::ArrayRef<frc::Pose2d> poses) override;
+  wpi::span<const frc::Pose2d> GetPoses() override { return m_poses; }
+  void SetPoses(wpi::span<const frc::Pose2d> poses) override;
   void SetPose(size_t i, frc::Pose2d pose) override;
   void SetPosition(size_t i, frc::Translation2d pos) override;
   void SetRotation(size_t i, frc::Rotation2d rot) override;
@@ -121,8 +121,8 @@ void NTField2DModel::ObjectModel::UpdateNT() {
   }
 }
 
-void NTField2DModel::ObjectModel::SetPoses(wpi::ArrayRef<frc::Pose2d> poses) {
-  m_poses = poses;
+void NTField2DModel::ObjectModel::SetPoses(wpi::span<const frc::Pose2d> poses) {
+  m_poses.assign(poses.begin(), poses.end());
   UpdateNT();
 }
 
diff --git a/glass/src/libnt/native/cpp/NTStringChooser.cpp b/glass/src/libnt/native/cpp/NTStringChooser.cpp
index 47eb787ea5..e6a97fae93 100644
--- a/glass/src/libnt/native/cpp/NTStringChooser.cpp
+++ b/glass/src/libnt/native/cpp/NTStringChooser.cpp
@@ -35,7 +35,7 @@ void NTStringChooserModel::SetActive(std::string_view val) {
   nt::SetEntryValue(m_active, nt::Value::MakeString(val));
 }
 
-void NTStringChooserModel::SetOptions(wpi::ArrayRef<std::string> val) {
+void NTStringChooserModel::SetOptions(wpi::span<const std::string> val) {
   nt::SetEntryValue(m_options, nt::Value::MakeStringArray(val));
 }
 
@@ -63,7 +63,8 @@ void NTStringChooserModel::Update() {
       if ((event.flags & NT_NOTIFY_DELETE) != 0) {
         m_optionsValue.clear();
       } else if (event.value && event.value->IsStringArray()) {
-        m_optionsValue = event.value->GetStringArray();
+        auto arr = event.value->GetStringArray();
+        m_optionsValue.assign(arr.begin(), arr.end());
       }
     }
   }
diff --git a/glass/src/libnt/native/cpp/NetworkTables.cpp b/glass/src/libnt/native/cpp/NetworkTables.cpp
index 0e0955d3ce..596ef0a0ca 100644
--- a/glass/src/libnt/native/cpp/NetworkTables.cpp
+++ b/glass/src/libnt/native/cpp/NetworkTables.cpp
@@ -17,17 +17,18 @@
 #include <fmt/format.h>
 #include <imgui.h>
 #include <ntcore_cpp.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallString.h>
+#include <wpi/SpanExtras.h>
 #include <wpi/StringExtras.h>
 #include <wpi/raw_ostream.h>
+#include <wpi/span.h>
 
 #include "glass/Context.h"
 #include "glass/DataSource.h"
 
 using namespace glass;
 
-static std::string BooleanArrayToString(wpi::ArrayRef<int> in) {
+static std::string BooleanArrayToString(wpi::span<const int> in) {
   std::string rv;
   wpi::raw_string_ostream os{rv};
   os << '[';
@@ -47,11 +48,11 @@ static std::string BooleanArrayToString(wpi::ArrayRef<int> in) {
   return rv;
 }
 
-static std::string DoubleArrayToString(wpi::ArrayRef<double> in) {
+static std::string DoubleArrayToString(wpi::span<const double> in) {
   return fmt::format("[{:.6f}]", fmt::join(in, ","));
 }
 
-static std::string StringArrayToString(wpi::ArrayRef<std::string> in) {
+static std::string StringArrayToString(wpi::span<const std::string> in) {
   std::string rv;
   wpi::raw_string_ostream os{rv};
   os << '[';
@@ -186,7 +187,7 @@ void NetworkTablesModel::Update() {
 
     // get to leaf
     auto nodes = &m_root;
-    for (auto part : wpi::ArrayRef(parts.begin(), parts.end()).drop_back()) {
+    for (auto part : wpi::drop_back(wpi::span{parts.begin(), parts.end()})) {
       auto it =
           std::find_if(nodes->begin(), nodes->end(),
                        [&](const auto& node) { return node.name == part; });
diff --git a/glass/src/libnt/native/include/glass/networktables/NTStringChooser.h b/glass/src/libnt/native/include/glass/networktables/NTStringChooser.h
index fac9f7c53a..2d806c9778 100644
--- a/glass/src/libnt/native/include/glass/networktables/NTStringChooser.h
+++ b/glass/src/libnt/native/include/glass/networktables/NTStringChooser.h
@@ -32,7 +32,7 @@ class NTStringChooserModel : public StringChooserModel {
   void SetDefault(std::string_view val) override;
   void SetSelected(std::string_view val) override;
   void SetActive(std::string_view val) override;
-  void SetOptions(wpi::ArrayRef<std::string> val) override;
+  void SetOptions(wpi::span<const std::string> val) override;
 
   void Update() override;
   bool Exists() override;
diff --git a/hal/src/main/native/cpp/jni/simulation/AddressableLEDDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/AddressableLEDDataJNI.cpp
index 52a4fb53b5..e888bd3ca9 100644
--- a/hal/src/main/native/cpp/jni/simulation/AddressableLEDDataJNI.cpp
+++ b/hal/src/main/native/cpp/jni/simulation/AddressableLEDDataJNI.cpp
@@ -257,7 +257,7 @@ Java_edu_wpi_first_hal_simulation_AddressableLEDDataJNI_getData
       std::make_unique<HAL_AddressableLEDData[]>(HAL_kAddressableLEDMaxLength);
   int32_t length = HALSIM_GetAddressableLEDData(index, data.get());
   return MakeJByteArray(
-      env, wpi::ArrayRef(reinterpret_cast<jbyte*>(data.get()), length * 4));
+      env, wpi::span(reinterpret_cast<jbyte*>(data.get()), length * 4));
 }
 
 /*
diff --git a/hal/src/main/native/cpp/jni/simulation/SimDeviceDataJNI.cpp b/hal/src/main/native/cpp/jni/simulation/SimDeviceDataJNI.cpp
index 51a3f0746c..60ce0f7a77 100644
--- a/hal/src/main/native/cpp/jni/simulation/SimDeviceDataJNI.cpp
+++ b/hal/src/main/native/cpp/jni/simulation/SimDeviceDataJNI.cpp
@@ -668,7 +668,7 @@ Java_edu_wpi_first_hal_simulation_SimDeviceDataJNI_getSimValueEnumDoubleValues
 {
   int32_t numElems = 0;
   const double* elems = HALSIM_GetSimValueEnumDoubleValues(handle, &numElems);
-  return MakeJDoubleArray(env, wpi::makeArrayRef(elems, numElems));
+  return MakeJDoubleArray(env, wpi::span(elems, numElems));
 }
 
 /*
diff --git a/hal/src/main/native/cpp/jni/simulation/SpiReadAutoReceiveBufferCallbackStore.cpp b/hal/src/main/native/cpp/jni/simulation/SpiReadAutoReceiveBufferCallbackStore.cpp
index 8d43e6fa2f..c20f60729f 100644
--- a/hal/src/main/native/cpp/jni/simulation/SpiReadAutoReceiveBufferCallbackStore.cpp
+++ b/hal/src/main/native/cpp/jni/simulation/SpiReadAutoReceiveBufferCallbackStore.cpp
@@ -59,7 +59,7 @@ int32_t SpiReadAutoReceiveBufferCallbackStore::performCallback(
   }
 
   auto toCallbackArr = MakeJIntArray(
-      env, wpi::ArrayRef<uint32_t>{buffer, static_cast<size_t>(numToRead)});
+      env, wpi::span<const uint32_t>{buffer, static_cast<size_t>(numToRead)});
 
   jint ret = env->CallIntMethod(m_call, sim::GetBufferCallback(),
                                 MakeJString(env, name), toCallbackArr,
diff --git a/hal/src/main/native/include/hal/SimDevice.h b/hal/src/main/native/include/hal/SimDevice.h
index ae319da455..7c0cf2d336 100644
--- a/hal/src/main/native/include/hal/SimDevice.h
+++ b/hal/src/main/native/include/hal/SimDevice.h
@@ -9,7 +9,7 @@
 #ifdef __cplusplus
 #include <initializer_list>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 #endif
 
 #include "hal/Types.h"
@@ -832,7 +832,8 @@ class SimDevice {
    * @return simulated enum value object
    */
   SimEnum CreateEnum(const char* name, int32_t direction,
-                     wpi::ArrayRef<const char*> options, int32_t initialValue) {
+                     wpi::span<const char* const> options,
+                     int32_t initialValue) {
     return HAL_CreateSimValueEnum(m_handle, name, direction, options.size(),
                                   const_cast<const char**>(options.data()),
                                   initialValue);
@@ -884,8 +885,8 @@ class SimDevice {
    * @return simulated enum value object
    */
   SimEnum CreateEnumDouble(const char* name, int32_t direction,
-                           wpi::ArrayRef<const char*> options,
-                           wpi::ArrayRef<double> optionValues,
+                           wpi::span<const char* const> options,
+                           wpi::span<const double> optionValues,
                            int32_t initialValue) {
     if (options.size() != optionValues.size()) {
       return {};
diff --git a/ntcore/src/main/native/cpp/Dispatcher.cpp b/ntcore/src/main/native/cpp/Dispatcher.cpp
index f0416f54ed..84d9698cf9 100644
--- a/ntcore/src/main/native/cpp/Dispatcher.cpp
+++ b/ntcore/src/main/native/cpp/Dispatcher.cpp
@@ -7,6 +7,7 @@
 #include <algorithm>
 #include <iterator>
 
+#include <wpi/SmallVector.h>
 #include <wpi/StringExtras.h>
 #include <wpi/TCPAcceptor.h>
 #include <wpi/TCPConnector.h>
@@ -37,7 +38,7 @@ void Dispatcher::SetServer(const char* server_name, unsigned int port) {
 }
 
 void Dispatcher::SetServer(
-    wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers) {
+    wpi::span<const std::pair<std::string_view, unsigned int>> servers) {
   wpi::SmallVector<std::pair<std::string, int>, 16> servers_copy;
   for (const auto& server : servers) {
     servers_copy.emplace_back(std::string{wpi::trim(server.first)},
@@ -512,7 +513,7 @@ void DispatcherBase::ClientThreadMain() {
 
 bool DispatcherBase::ClientHandshake(
     NetworkConnection& conn, std::function<std::shared_ptr<Message>()> get_msg,
-    std::function<void(wpi::ArrayRef<std::shared_ptr<Message>>)> send_msgs) {
+    std::function<void(wpi::span<std::shared_ptr<Message>>)> send_msgs) {
   // get identity
   std::string self_id;
   {
@@ -522,10 +523,11 @@ bool DispatcherBase::ClientHandshake(
 
   // send client hello
   DEBUG0("{}", "client: sending hello");
-  send_msgs(Message::ClientHello(self_id));
+  auto msg = Message::ClientHello(self_id);
+  send_msgs(wpi::span(&msg, 1));
 
   // wait for response
-  auto msg = get_msg();
+  msg = get_msg();
   if (!msg) {
     // disconnected, retry
     DEBUG0("{}", "client: server disconnected before first response");
@@ -604,7 +606,7 @@ bool DispatcherBase::ClientHandshake(
 
 bool DispatcherBase::ServerHandshake(
     NetworkConnection& conn, std::function<std::shared_ptr<Message>()> get_msg,
-    std::function<void(wpi::ArrayRef<std::shared_ptr<Message>>)> send_msgs) {
+    std::function<void(wpi::span<std::shared_ptr<Message>>)> send_msgs) {
   // Wait for the client to send us a hello.
   auto msg = get_msg();
   if (!msg) {
@@ -620,7 +622,8 @@ bool DispatcherBase::ServerHandshake(
   unsigned int proto_rev = msg->id();
   if (proto_rev > 0x0300) {
     DEBUG0("{}", "server: client requested proto > 0x0300");
-    send_msgs(Message::ProtoUnsup());
+    auto toSend = Message::ProtoUnsup();
+    send_msgs(wpi::span(&toSend, 1));
     return false;
   }
 
diff --git a/ntcore/src/main/native/cpp/Dispatcher.h b/ntcore/src/main/native/cpp/Dispatcher.h
index c18b0b4caf..a2a742531e 100644
--- a/ntcore/src/main/native/cpp/Dispatcher.h
+++ b/ntcore/src/main/native/cpp/Dispatcher.h
@@ -16,6 +16,7 @@
 
 #include <wpi/condition_variable.h>
 #include <wpi/mutex.h>
+#include <wpi/span.h>
 
 #include "IDispatcher.h"
 #include "INetworkConnection.h"
@@ -77,11 +78,11 @@ class DispatcherBase : public IDispatcher {
   bool ClientHandshake(
       NetworkConnection& conn,
       std::function<std::shared_ptr<Message>()> get_msg,
-      std::function<void(wpi::ArrayRef<std::shared_ptr<Message>>)> send_msgs);
+      std::function<void(wpi::span<std::shared_ptr<Message>>)> send_msgs);
   bool ServerHandshake(
       NetworkConnection& conn,
       std::function<std::shared_ptr<Message>()> get_msg,
-      std::function<void(wpi::ArrayRef<std::shared_ptr<Message>>)> send_msgs);
+      std::function<void(wpi::span<std::shared_ptr<Message>>)> send_msgs);
 
   void ClientReconnect(unsigned int proto_rev = 0x0300);
 
@@ -136,7 +137,7 @@ class Dispatcher : public DispatcherBase {
 
   void SetServer(const char* server_name, unsigned int port);
   void SetServer(
-      wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers);
+      wpi::span<const std::pair<std::string_view, unsigned int>> servers);
   void SetServerTeam(unsigned int team, unsigned int port);
 
   void SetServerOverride(const char* server_name, unsigned int port);
diff --git a/ntcore/src/main/native/cpp/IStorage.h b/ntcore/src/main/native/cpp/IStorage.h
index d547d51dff..795d032970 100644
--- a/ntcore/src/main/native/cpp/IStorage.h
+++ b/ntcore/src/main/native/cpp/IStorage.h
@@ -10,7 +10,7 @@
 #include <string_view>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "Message.h"
 #include "ntcore_cpp.h"
@@ -45,7 +45,7 @@ class IStorage {
       INetworkConnection& conn,
       std::vector<std::shared_ptr<Message>>* msgs) = 0;
   virtual void ApplyInitialAssignments(
-      INetworkConnection& conn, wpi::ArrayRef<std::shared_ptr<Message>> msgs,
+      INetworkConnection& conn, wpi::span<std::shared_ptr<Message>> msgs,
       bool new_server, std::vector<std::shared_ptr<Message>>* out_msgs) = 0;
 
   // Filename-based save/load functions.  Used both by periodic saves and
diff --git a/ntcore/src/main/native/cpp/NetworkConnection.cpp b/ntcore/src/main/native/cpp/NetworkConnection.cpp
index ffc45c5b65..838eecbc45 100644
--- a/ntcore/src/main/native/cpp/NetworkConnection.cpp
+++ b/ntcore/src/main/native/cpp/NetworkConnection.cpp
@@ -162,8 +162,9 @@ void NetworkConnection::ReadThreadMain() {
             }
             return msg;
           },
-          [&](wpi::ArrayRef<std::shared_ptr<Message>> msgs) {
-            m_outgoing.emplace(msgs);
+          [&](auto msgs) {
+            m_outgoing.emplace(std::vector<std::shared_ptr<Message>>(
+                msgs.begin(), msgs.end()));
           })) {
     set_state(kDead);
     m_active = false;
diff --git a/ntcore/src/main/native/cpp/NetworkConnection.h b/ntcore/src/main/native/cpp/NetworkConnection.h
index 412b91702f..e023320caf 100644
--- a/ntcore/src/main/native/cpp/NetworkConnection.h
+++ b/ntcore/src/main/native/cpp/NetworkConnection.h
@@ -19,6 +19,7 @@
 #include <wpi/ConcurrentQueue.h>
 #include <wpi/condition_variable.h>
 #include <wpi/mutex.h>
+#include <wpi/span.h>
 
 #include "INetworkConnection.h"
 #include "Message.h"
@@ -38,7 +39,7 @@ class NetworkConnection : public INetworkConnection {
   typedef std::function<bool(
       NetworkConnection& conn,
       std::function<std::shared_ptr<Message>()> get_msg,
-      std::function<void(wpi::ArrayRef<std::shared_ptr<Message>>)> send_msgs)>
+      std::function<void(wpi::span<std::shared_ptr<Message>>)> send_msgs)>
       HandshakeFunc;
   using ProcessIncomingFunc =
       std::function<void(std::shared_ptr<Message>, NetworkConnection*)>;
diff --git a/ntcore/src/main/native/cpp/Storage.cpp b/ntcore/src/main/native/cpp/Storage.cpp
index 9e8bd83c06..dadc3f6637 100644
--- a/ntcore/src/main/native/cpp/Storage.cpp
+++ b/ntcore/src/main/native/cpp/Storage.cpp
@@ -410,7 +410,7 @@ void Storage::GetInitialAssignments(
 }
 
 void Storage::ApplyInitialAssignments(
-    INetworkConnection& conn, wpi::ArrayRef<std::shared_ptr<Message>> msgs,
+    INetworkConnection& conn, wpi::span<std::shared_ptr<Message>> msgs,
     bool /*new_server*/, std::vector<std::shared_ptr<Message>>* out_msgs) {
   std::unique_lock lock(m_mutex);
   if (m_server) {
diff --git a/ntcore/src/main/native/cpp/Storage.h b/ntcore/src/main/native/cpp/Storage.h
index 3ca834cdb2..add675ebfd 100644
--- a/ntcore/src/main/native/cpp/Storage.h
+++ b/ntcore/src/main/native/cpp/Storage.h
@@ -21,6 +21,7 @@
 #include <wpi/StringMap.h>
 #include <wpi/condition_variable.h>
 #include <wpi/mutex.h>
+#include <wpi/span.h>
 
 #include "IStorage.h"
 #include "Message.h"
@@ -67,7 +68,7 @@ class Storage : public IStorage {
       INetworkConnection& conn,
       std::vector<std::shared_ptr<Message>>* msgs) override;
   void ApplyInitialAssignments(
-      INetworkConnection& conn, wpi::ArrayRef<std::shared_ptr<Message>> msgs,
+      INetworkConnection& conn, wpi::span<std::shared_ptr<Message>> msgs,
       bool new_server,
       std::vector<std::shared_ptr<Message>>* out_msgs) override;
 
diff --git a/ntcore/src/main/native/cpp/Storage_save.cpp b/ntcore/src/main/native/cpp/Storage_save.cpp
index 26e0cad983..6d5db9f83a 100644
--- a/ntcore/src/main/native/cpp/Storage_save.cpp
+++ b/ntcore/src/main/native/cpp/Storage_save.cpp
@@ -25,12 +25,12 @@ class SavePersistentImpl {
 
   explicit SavePersistentImpl(wpi::raw_ostream& os) : m_os(os) {}
 
-  void Save(wpi::ArrayRef<Entry> entries);
+  void Save(wpi::span<const Entry> entries);
 
  private:
   void WriteString(std::string_view str);
   void WriteHeader();
-  void WriteEntries(wpi::ArrayRef<Entry> entries);
+  void WriteEntries(wpi::span<const Entry> entries);
   void WriteEntry(std::string_view name, const Value& value);
   bool WriteType(NT_Type type);
   void WriteValue(const Value& value);
@@ -72,7 +72,7 @@ void SavePersistentImpl::WriteString(std::string_view str) {
   m_os << '"';
 }
 
-void SavePersistentImpl::Save(wpi::ArrayRef<Entry> entries) {
+void SavePersistentImpl::Save(wpi::span<const Entry> entries) {
   WriteHeader();
   WriteEntries(entries);
 }
@@ -81,7 +81,7 @@ void SavePersistentImpl::WriteHeader() {
   m_os << "[NetworkTables Storage 3.0]\n";
 }
 
-void SavePersistentImpl::WriteEntries(wpi::ArrayRef<Entry> entries) {
+void SavePersistentImpl::WriteEntries(wpi::span<const Entry> entries) {
   for (auto& i : entries) {
     if (!i.second) {
       continue;
diff --git a/ntcore/src/main/native/cpp/Value.cpp b/ntcore/src/main/native/cpp/Value.cpp
index 96af67a551..e0d65c998b 100644
--- a/ntcore/src/main/native/cpp/Value.cpp
+++ b/ntcore/src/main/native/cpp/Value.cpp
@@ -4,6 +4,8 @@
 
 #include <stdint.h>
 
+#include <cstring>
+
 #include <wpi/MemAlloc.h>
 #include <wpi/timestamp.h>
 
@@ -43,7 +45,7 @@ Value::~Value() {
   }
 }
 
-std::shared_ptr<Value> Value::MakeBooleanArray(wpi::ArrayRef<bool> value,
+std::shared_ptr<Value> Value::MakeBooleanArray(wpi::span<const bool> value,
                                                uint64_t time) {
   auto val = std::make_shared<Value>(NT_BOOLEAN_ARRAY, time, private_init());
   val->m_val.data.arr_boolean.arr = new int[value.size()];
@@ -52,7 +54,7 @@ std::shared_ptr<Value> Value::MakeBooleanArray(wpi::ArrayRef<bool> value,
   return val;
 }
 
-std::shared_ptr<Value> Value::MakeBooleanArray(wpi::ArrayRef<int> value,
+std::shared_ptr<Value> Value::MakeBooleanArray(wpi::span<const int> value,
                                                uint64_t time) {
   auto val = std::make_shared<Value>(NT_BOOLEAN_ARRAY, time, private_init());
   val->m_val.data.arr_boolean.arr = new int[value.size()];
@@ -61,7 +63,7 @@ std::shared_ptr<Value> Value::MakeBooleanArray(wpi::ArrayRef<int> value,
   return val;
 }
 
-std::shared_ptr<Value> Value::MakeDoubleArray(wpi::ArrayRef<double> value,
+std::shared_ptr<Value> Value::MakeDoubleArray(wpi::span<const double> value,
                                               uint64_t time) {
   auto val = std::make_shared<Value>(NT_DOUBLE_ARRAY, time, private_init());
   val->m_val.data.arr_double.arr = new double[value.size()];
@@ -70,10 +72,10 @@ std::shared_ptr<Value> Value::MakeDoubleArray(wpi::ArrayRef<double> value,
   return val;
 }
 
-std::shared_ptr<Value> Value::MakeStringArray(wpi::ArrayRef<std::string> value,
-                                              uint64_t time) {
+std::shared_ptr<Value> Value::MakeStringArray(
+    wpi::span<const std::string> value, uint64_t time) {
   auto val = std::make_shared<Value>(NT_STRING_ARRAY, time, private_init());
-  val->m_string_array = value;
+  val->m_string_array.assign(value.begin(), value.end());
   // point NT_Value to the contents in the vector.
   val->m_val.data.arr_string.arr = new NT_String[value.size()];
   val->m_val.data.arr_string.size = val->m_string_array.size();
@@ -175,11 +177,11 @@ std::shared_ptr<Value> nt::ConvertFromC(const NT_Value& value) {
     case NT_RPC:
       return Value::MakeRpc(ConvertFromC(value.data.v_raw));
     case NT_BOOLEAN_ARRAY:
-      return Value::MakeBooleanArray(wpi::ArrayRef<int>(
-          value.data.arr_boolean.arr, value.data.arr_boolean.size));
+      return Value::MakeBooleanArray(
+          wpi::span(value.data.arr_boolean.arr, value.data.arr_boolean.size));
     case NT_DOUBLE_ARRAY:
-      return Value::MakeDoubleArray(wpi::ArrayRef<double>(
-          value.data.arr_double.arr, value.data.arr_double.size));
+      return Value::MakeDoubleArray(
+          wpi::span(value.data.arr_double.arr, value.data.arr_double.size));
     case NT_STRING_ARRAY: {
       std::vector<std::string> v;
       v.reserve(value.data.arr_string.size);
diff --git a/ntcore/src/main/native/cpp/jni/NetworkTablesJNI.cpp b/ntcore/src/main/native/cpp/jni/NetworkTablesJNI.cpp
index b3f943c0fa..6c7ed82683 100644
--- a/ntcore/src/main/native/cpp/jni/NetworkTablesJNI.cpp
+++ b/ntcore/src/main/native/cpp/jni/NetworkTablesJNI.cpp
@@ -139,7 +139,7 @@ std::shared_ptr<nt::Value> FromJavaBooleanArray(JNIEnv* env, jbooleanArray jarr,
   if (!ref) {
     return nullptr;
   }
-  wpi::ArrayRef<jboolean> elements{ref};
+  wpi::span<const jboolean> elements{ref};
   size_t len = elements.size();
   std::vector<int> arr;
   arr.reserve(len);
@@ -306,8 +306,9 @@ static jobject MakeJObject(JNIEnv* env, jobject inst,
       static_cast<jint>(answer.call), name.obj(), params.obj(), conn.obj());
 }
 
-static jobjectArray MakeJObject(JNIEnv* env, jobject inst,
-                                wpi::ArrayRef<nt::ConnectionNotification> arr) {
+static jobjectArray MakeJObject(
+    JNIEnv* env, jobject inst,
+    wpi::span<const nt::ConnectionNotification> arr) {
   jobjectArray jarr =
       env->NewObjectArray(arr.size(), connectionNotificationCls, nullptr);
   if (!jarr) {
@@ -321,7 +322,7 @@ static jobjectArray MakeJObject(JNIEnv* env, jobject inst,
 }
 
 static jobjectArray MakeJObject(JNIEnv* env, jobject inst,
-                                wpi::ArrayRef<nt::EntryNotification> arr) {
+                                wpi::span<const nt::EntryNotification> arr) {
   jobjectArray jarr =
       env->NewObjectArray(arr.size(), entryNotificationCls, nullptr);
   if (!jarr) {
@@ -335,7 +336,7 @@ static jobjectArray MakeJObject(JNIEnv* env, jobject inst,
 }
 
 static jobjectArray MakeJObject(JNIEnv* env, jobject inst,
-                                wpi::ArrayRef<nt::LogMessage> arr) {
+                                wpi::span<const nt::LogMessage> arr) {
   jobjectArray jarr = env->NewObjectArray(arr.size(), logMessageCls, nullptr);
   if (!jarr) {
     return nullptr;
@@ -348,7 +349,7 @@ static jobjectArray MakeJObject(JNIEnv* env, jobject inst,
 }
 
 static jobjectArray MakeJObject(JNIEnv* env, jobject inst,
-                                wpi::ArrayRef<nt::RpcAnswer> arr) {
+                                wpi::span<const nt::RpcAnswer> arr) {
   jobjectArray jarr = env->NewObjectArray(arr.size(), rpcAnswerCls, nullptr);
   if (!jarr) {
     return nullptr;
diff --git a/ntcore/src/main/native/cpp/networktables/NetworkTable.cpp b/ntcore/src/main/native/cpp/networktables/NetworkTable.cpp
index 25bd809f02..017d0af2ed 100644
--- a/ntcore/src/main/native/cpp/networktables/NetworkTable.cpp
+++ b/ntcore/src/main/native/cpp/networktables/NetworkTable.cpp
@@ -288,47 +288,47 @@ bool NetworkTable::GetBoolean(std::string_view key, bool defaultValue) const {
 }
 
 bool NetworkTable::PutBooleanArray(std::string_view key,
-                                   wpi::ArrayRef<int> value) {
+                                   wpi::span<const int> value) {
   return GetEntry(key).SetBooleanArray(value);
 }
 
 bool NetworkTable::SetDefaultBooleanArray(std::string_view key,
-                                          wpi::ArrayRef<int> defaultValue) {
+                                          wpi::span<const int> defaultValue) {
   return GetEntry(key).SetDefaultBooleanArray(defaultValue);
 }
 
 std::vector<int> NetworkTable::GetBooleanArray(
-    std::string_view key, wpi::ArrayRef<int> defaultValue) const {
+    std::string_view key, wpi::span<const int> defaultValue) const {
   return GetEntry(key).GetBooleanArray(defaultValue);
 }
 
 bool NetworkTable::PutNumberArray(std::string_view key,
-                                  wpi::ArrayRef<double> value) {
+                                  wpi::span<const double> value) {
   return GetEntry(key).SetDoubleArray(value);
 }
 
 bool NetworkTable::SetDefaultNumberArray(std::string_view key,
-                                         wpi::ArrayRef<double> defaultValue) {
+                                         wpi::span<const double> defaultValue) {
   return GetEntry(key).SetDefaultDoubleArray(defaultValue);
 }
 
 std::vector<double> NetworkTable::GetNumberArray(
-    std::string_view key, wpi::ArrayRef<double> defaultValue) const {
+    std::string_view key, wpi::span<const double> defaultValue) const {
   return GetEntry(key).GetDoubleArray(defaultValue);
 }
 
 bool NetworkTable::PutStringArray(std::string_view key,
-                                  wpi::ArrayRef<std::string> value) {
+                                  wpi::span<const std::string> value) {
   return GetEntry(key).SetStringArray(value);
 }
 
 bool NetworkTable::SetDefaultStringArray(
-    std::string_view key, wpi::ArrayRef<std::string> defaultValue) {
+    std::string_view key, wpi::span<const std::string> defaultValue) {
   return GetEntry(key).SetDefaultStringArray(defaultValue);
 }
 
 std::vector<std::string> NetworkTable::GetStringArray(
-    std::string_view key, wpi::ArrayRef<std::string> defaultValue) const {
+    std::string_view key, wpi::span<const std::string> defaultValue) const {
   return GetEntry(key).GetStringArray(defaultValue);
 }
 
diff --git a/ntcore/src/main/native/cpp/networktables/NetworkTableInstance.cpp b/ntcore/src/main/native/cpp/networktables/NetworkTableInstance.cpp
index 4ff8f7551b..4566b30529 100644
--- a/ntcore/src/main/native/cpp/networktables/NetworkTableInstance.cpp
+++ b/ntcore/src/main/native/cpp/networktables/NetworkTableInstance.cpp
@@ -23,8 +23,8 @@ std::shared_ptr<NetworkTable> NetworkTableInstance::GetTable(
   }
 }
 
-void NetworkTableInstance::StartClient(wpi::ArrayRef<std::string_view> servers,
-                                       unsigned int port) {
+void NetworkTableInstance::StartClient(
+    wpi::span<const std::string_view> servers, unsigned int port) {
   wpi::SmallVector<std::pair<std::string_view, unsigned int>, 8> server_ports;
   for (const auto& server : servers) {
     server_ports.emplace_back(std::make_pair(server, port));
@@ -32,7 +32,7 @@ void NetworkTableInstance::StartClient(wpi::ArrayRef<std::string_view> servers,
   StartClient(server_ports);
 }
 
-void NetworkTableInstance::SetServer(wpi::ArrayRef<std::string_view> servers,
+void NetworkTableInstance::SetServer(wpi::span<const std::string_view> servers,
                                      unsigned int port) {
   wpi::SmallVector<std::pair<std::string_view, unsigned int>, 8> server_ports;
   for (const auto& server : servers) {
diff --git a/ntcore/src/main/native/cpp/ntcore_c.cpp b/ntcore/src/main/native/cpp/ntcore_c.cpp
index ae48b1cce6..c5a8e497c5 100644
--- a/ntcore/src/main/native/cpp/ntcore_c.cpp
+++ b/ntcore/src/main/native/cpp/ntcore_c.cpp
@@ -6,6 +6,7 @@
 
 #include <cassert>
 #include <cstdlib>
+#include <cstring>
 #include <string_view>
 
 #include <wpi/MemAlloc.h>
@@ -550,8 +551,7 @@ char* NT_PackRpcValues(const NT_Value** values, size_t values_len,
 
 NT_Value** NT_UnpackRpcValues(const char* packed, size_t packed_len,
                               const NT_Type* types, size_t types_len) {
-  auto values_v = nt::UnpackRpcValues({packed, packed_len},
-                                      wpi::ArrayRef<NT_Type>(types, types_len));
+  auto values_v = nt::UnpackRpcValues({packed, packed_len}, {types, types_len});
   if (values_v.size() == 0) {
     return nullptr;
   }
@@ -972,24 +972,22 @@ NT_Bool NT_SetEntryBooleanArray(NT_Entry entry, uint64_t time,
                                 const NT_Bool* arr, size_t size,
                                 NT_Bool force) {
   if (force != 0) {
-    nt::SetEntryTypeValue(
-        entry, Value::MakeBooleanArray(wpi::makeArrayRef(arr, size), time));
+    nt::SetEntryTypeValue(entry,
+                          Value::MakeBooleanArray(wpi::span(arr, size), time));
     return 1;
   } else {
     return nt::SetEntryValue(
-        entry, Value::MakeBooleanArray(wpi::makeArrayRef(arr, size), time));
+        entry, Value::MakeBooleanArray(wpi::span(arr, size), time));
   }
 }
 
 NT_Bool NT_SetEntryDoubleArray(NT_Entry entry, uint64_t time, const double* arr,
                                size_t size, NT_Bool force) {
   if (force != 0) {
-    nt::SetEntryTypeValue(
-        entry, Value::MakeDoubleArray(wpi::makeArrayRef(arr, size), time));
+    nt::SetEntryTypeValue(entry, Value::MakeDoubleArray({arr, size}, time));
     return 1;
   } else {
-    return nt::SetEntryValue(
-        entry, Value::MakeDoubleArray(wpi::makeArrayRef(arr, size), time));
+    return nt::SetEntryValue(entry, Value::MakeDoubleArray({arr, size}, time));
   }
 }
 
@@ -1138,16 +1136,15 @@ NT_Bool NT_SetDefaultEntryBooleanArray(NT_Entry entry, uint64_t time,
                                        const NT_Bool* default_value,
                                        size_t default_size) {
   return nt::SetDefaultEntryValue(
-      entry, Value::MakeBooleanArray(
-                 wpi::makeArrayRef(default_value, default_size), time));
+      entry,
+      Value::MakeBooleanArray(wpi::span(default_value, default_size), time));
 }
 
 NT_Bool NT_SetDefaultEntryDoubleArray(NT_Entry entry, uint64_t time,
                                       const double* default_value,
                                       size_t default_size) {
   return nt::SetDefaultEntryValue(
-      entry, Value::MakeDoubleArray(
-                 wpi::makeArrayRef(default_value, default_size), time));
+      entry, Value::MakeDoubleArray({default_value, default_size}, time));
 }
 
 NT_Bool NT_SetDefaultEntryStringArray(NT_Entry entry, uint64_t time,
diff --git a/ntcore/src/main/native/cpp/ntcore_cpp.cpp b/ntcore/src/main/native/cpp/ntcore_cpp.cpp
index 619e996941..ae85e46b26 100644
--- a/ntcore/src/main/native/cpp/ntcore_cpp.cpp
+++ b/ntcore/src/main/native/cpp/ntcore_cpp.cpp
@@ -792,7 +792,7 @@ bool UnpackRpcDefinition(std::string_view packed, RpcDefinition* def) {
   return true;
 }
 
-std::string PackRpcValues(wpi::ArrayRef<std::shared_ptr<Value>> values) {
+std::string PackRpcValues(wpi::span<const std::shared_ptr<Value>> values) {
   WireEncoder enc(0x0300);
   for (auto& value : values) {
     enc.WriteValue(*value);
@@ -801,7 +801,7 @@ std::string PackRpcValues(wpi::ArrayRef<std::shared_ptr<Value>> values) {
 }
 
 std::vector<std::shared_ptr<Value>> UnpackRpcValues(
-    std::string_view packed, wpi::ArrayRef<NT_Type> types) {
+    std::string_view packed, wpi::span<const NT_Type> types) {
   wpi::raw_mem_istream is(packed.data(), packed.size());
   wpi::Logger logger;
   WireDecoder dec(is, 0x0300, logger);
@@ -900,7 +900,7 @@ void StartClient(NT_Inst inst, const char* server_name, unsigned int port) {
 
 void StartClient(
     NT_Inst inst,
-    wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers) {
+    wpi::span<const std::pair<std::string_view, unsigned int>> servers) {
   auto ii = InstanceImpl::Get(Handle{inst}.GetTypedInst(Handle::kInstance));
   if (!ii) {
     return;
@@ -940,7 +940,7 @@ void SetServer(NT_Inst inst, const char* server_name, unsigned int port) {
 
 void SetServer(
     NT_Inst inst,
-    wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers) {
+    wpi::span<const std::pair<std::string_view, unsigned int>> servers) {
   auto ii = InstanceImpl::Get(Handle{inst}.GetTypedInst(Handle::kInstance));
   if (!ii) {
     return;
diff --git a/ntcore/src/main/native/cpp/ntcore_test.cpp b/ntcore/src/main/native/cpp/ntcore_test.cpp
index 00d07f7b27..64bde688db 100644
--- a/ntcore/src/main/native/cpp/ntcore_test.cpp
+++ b/ntcore/src/main/native/cpp/ntcore_test.cpp
@@ -4,6 +4,8 @@
 
 #include "ntcore_test.h"
 
+#include <cstring>
+
 #include <wpi/MemAlloc.h>
 
 #include "Value_internal.h"
diff --git a/ntcore/src/main/native/include/networktables/NetworkTable.h b/ntcore/src/main/native/include/networktables/NetworkTable.h
index 7ac4e7eb14..3a04e45222 100644
--- a/ntcore/src/main/native/include/networktables/NetworkTable.h
+++ b/ntcore/src/main/native/include/networktables/NetworkTable.h
@@ -12,9 +12,9 @@
 #include <utility>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
 #include <wpi/StringMap.h>
 #include <wpi/mutex.h>
+#include <wpi/span.h>
 
 #include "networktables/NetworkTableEntry.h"
 #include "networktables/TableEntryListener.h"
@@ -360,7 +360,7 @@ class NetworkTable final {
    *       std::vector<bool> is special-cased in C++.  0 is false, any
    *       non-zero value is true.
    */
-  bool PutBooleanArray(std::string_view key, wpi::ArrayRef<int> value);
+  bool PutBooleanArray(std::string_view key, wpi::span<const int> value);
 
   /**
    * Gets the current value in the table, setting it if it does not exist.
@@ -370,7 +370,7 @@ class NetworkTable final {
    * @return False if the table key exists with a different type
    */
   bool SetDefaultBooleanArray(std::string_view key,
-                              wpi::ArrayRef<int> defaultValue);
+                              wpi::span<const int> defaultValue);
 
   /**
    * Returns the boolean array the key maps to. If the key does not exist or is
@@ -389,7 +389,7 @@ class NetworkTable final {
    *       non-zero value is true.
    */
   std::vector<int> GetBooleanArray(std::string_view key,
-                                   wpi::ArrayRef<int> defaultValue) const;
+                                   wpi::span<const int> defaultValue) const;
 
   /**
    * Put a number array in the table
@@ -398,7 +398,7 @@ class NetworkTable final {
    * @param value the value that will be assigned
    * @return False if the table key already exists with a different type
    */
-  bool PutNumberArray(std::string_view key, wpi::ArrayRef<double> value);
+  bool PutNumberArray(std::string_view key, wpi::span<const double> value);
 
   /**
    * Gets the current value in the table, setting it if it does not exist.
@@ -408,7 +408,7 @@ class NetworkTable final {
    * @returns False if the table key exists with a different type
    */
   bool SetDefaultNumberArray(std::string_view key,
-                             wpi::ArrayRef<double> defaultValue);
+                             wpi::span<const double> defaultValue);
 
   /**
    * Returns the number array the key maps to. If the key does not exist or is
@@ -422,8 +422,8 @@ class NetworkTable final {
    * @note This makes a copy of the array.  If the overhead of this is a
    *       concern, use GetValue() instead.
    */
-  std::vector<double> GetNumberArray(std::string_view key,
-                                     wpi::ArrayRef<double> defaultValue) const;
+  std::vector<double> GetNumberArray(
+      std::string_view key, wpi::span<const double> defaultValue) const;
 
   /**
    * Put a string array in the table
@@ -432,7 +432,7 @@ class NetworkTable final {
    * @param value the value that will be assigned
    * @return False if the table key already exists with a different type
    */
-  bool PutStringArray(std::string_view key, wpi::ArrayRef<std::string> value);
+  bool PutStringArray(std::string_view key, wpi::span<const std::string> value);
 
   /**
    * Gets the current value in the table, setting it if it does not exist.
@@ -442,7 +442,7 @@ class NetworkTable final {
    * @returns False if the table key exists with a different type
    */
   bool SetDefaultStringArray(std::string_view key,
-                             wpi::ArrayRef<std::string> defaultValue);
+                             wpi::span<const std::string> defaultValue);
 
   /**
    * Returns the string array the key maps to. If the key does not exist or is
@@ -457,7 +457,7 @@ class NetworkTable final {
    *       concern, use GetValue() instead.
    */
   std::vector<std::string> GetStringArray(
-      std::string_view key, wpi::ArrayRef<std::string> defaultValue) const;
+      std::string_view key, wpi::span<const std::string> defaultValue) const;
 
   /**
    * Put a raw value (byte array) in the table
diff --git a/ntcore/src/main/native/include/networktables/NetworkTableEntry.h b/ntcore/src/main/native/include/networktables/NetworkTableEntry.h
index 7774fa2157..ff717ae583 100644
--- a/ntcore/src/main/native/include/networktables/NetworkTableEntry.h
+++ b/ntcore/src/main/native/include/networktables/NetworkTableEntry.h
@@ -13,6 +13,8 @@
 #include <string_view>
 #include <vector>
 
+#include <wpi/span.h>
+
 #include "networktables/NetworkTableType.h"
 #include "networktables/NetworkTableValue.h"
 #include "networktables/RpcCall.h"
@@ -166,7 +168,7 @@ class NetworkTableEntry final {
    *       because std::vector<bool> is special-cased in C++.  0 is false, any
    *       non-zero value is true.
    */
-  std::vector<int> GetBooleanArray(wpi::ArrayRef<int> defaultValue) const;
+  std::vector<int> GetBooleanArray(wpi::span<const int> defaultValue) const;
 
   /**
    * Gets the entry's value as a boolean array. If the entry does not exist
@@ -195,7 +197,8 @@ class NetworkTableEntry final {
    * @note This makes a copy of the array.  If the overhead of this is a
    *       concern, use GetValue() instead.
    */
-  std::vector<double> GetDoubleArray(wpi::ArrayRef<double> defaultValue) const;
+  std::vector<double> GetDoubleArray(
+      wpi::span<const double> defaultValue) const;
 
   /**
    * Gets the entry's value as a double array. If the entry does not exist
@@ -221,7 +224,7 @@ class NetworkTableEntry final {
    *       concern, use GetValue() instead.
    */
   std::vector<std::string> GetStringArray(
-      wpi::ArrayRef<std::string> defaultValue) const;
+      wpi::span<const std::string> defaultValue) const;
 
   /**
    * Gets the entry's value as a string array. If the entry does not exist
@@ -282,7 +285,7 @@ class NetworkTableEntry final {
    * @param defaultValue the default value to set
    * @return False if the entry exists with a different type
    */
-  bool SetDefaultBooleanArray(wpi::ArrayRef<int> defaultValue);
+  bool SetDefaultBooleanArray(wpi::span<const int> defaultValue);
 
   /**
    * Sets the entry's value if it does not exist.
@@ -298,7 +301,7 @@ class NetworkTableEntry final {
    * @param defaultValue the default value to set
    * @return False if the entry exists with a different type
    */
-  bool SetDefaultDoubleArray(wpi::ArrayRef<double> defaultValue);
+  bool SetDefaultDoubleArray(wpi::span<const double> defaultValue);
 
   /**
    * Sets the entry's value if it does not exist.
@@ -314,7 +317,7 @@ class NetworkTableEntry final {
    * @param defaultValue the default value to set
    * @return False if the entry exists with a different type
    */
-  bool SetDefaultStringArray(wpi::ArrayRef<std::string> defaultValue);
+  bool SetDefaultStringArray(wpi::span<const std::string> defaultValue);
 
   /**
    * Sets the entry's value if it does not exist.
@@ -370,7 +373,7 @@ class NetworkTableEntry final {
    * @param value the value to set
    * @return False if the entry exists with a different type
    */
-  bool SetBooleanArray(wpi::ArrayRef<bool> value);
+  bool SetBooleanArray(wpi::span<const bool> value);
 
   /**
    * Sets the entry's value.
@@ -386,7 +389,7 @@ class NetworkTableEntry final {
    * @param value the value to set
    * @return False if the entry exists with a different type
    */
-  bool SetBooleanArray(wpi::ArrayRef<int> value);
+  bool SetBooleanArray(wpi::span<const int> value);
 
   /**
    * Sets the entry's value.
@@ -402,7 +405,7 @@ class NetworkTableEntry final {
    * @param value the value to set
    * @return False if the entry exists with a different type
    */
-  bool SetDoubleArray(wpi::ArrayRef<double> value);
+  bool SetDoubleArray(wpi::span<const double> value);
 
   /**
    * Sets the entry's value.
@@ -418,7 +421,7 @@ class NetworkTableEntry final {
    * @param value the value to set
    * @return False if the entry exists with a different type
    */
-  bool SetStringArray(wpi::ArrayRef<std::string> value);
+  bool SetStringArray(wpi::span<const std::string> value);
 
   /**
    * Sets the entry's value.
@@ -474,7 +477,7 @@ class NetworkTableEntry final {
    *
    * @param value the value to set
    */
-  void ForceSetBooleanArray(wpi::ArrayRef<bool> value);
+  void ForceSetBooleanArray(wpi::span<const bool> value);
 
   /**
    * Sets the entry's value.  If the value is of different type, the type is
@@ -490,7 +493,7 @@ class NetworkTableEntry final {
    *
    * @param value the value to set
    */
-  void ForceSetBooleanArray(wpi::ArrayRef<int> value);
+  void ForceSetBooleanArray(wpi::span<const int> value);
 
   /**
    * Sets the entry's value.  If the value is of different type, the type is
@@ -506,7 +509,7 @@ class NetworkTableEntry final {
    *
    * @param value the value to set
    */
-  void ForceSetDoubleArray(wpi::ArrayRef<double> value);
+  void ForceSetDoubleArray(wpi::span<const double> value);
 
   /**
    * Sets the entry's value.  If the value is of different type, the type is
@@ -522,7 +525,7 @@ class NetworkTableEntry final {
    *
    * @param value the value to set
    */
-  void ForceSetStringArray(wpi::ArrayRef<std::string> value);
+  void ForceSetStringArray(wpi::span<const std::string> value);
 
   /**
    * Sets the entry's value.  If the value is of different type, the type is
diff --git a/ntcore/src/main/native/include/networktables/NetworkTableEntry.inc b/ntcore/src/main/native/include/networktables/NetworkTableEntry.inc
index 00082b3961..e7deb51733 100644
--- a/ntcore/src/main/native/include/networktables/NetworkTableEntry.inc
+++ b/ntcore/src/main/native/include/networktables/NetworkTableEntry.inc
@@ -86,48 +86,48 @@ inline std::string NetworkTableEntry::GetRaw(
 }
 
 inline std::vector<int> NetworkTableEntry::GetBooleanArray(
-    wpi::ArrayRef<int> defaultValue) const {
+    wpi::span<const int> defaultValue) const {
   auto value = GetEntryValue(m_handle);
   if (!value || value->type() != NT_BOOLEAN_ARRAY) {
-    return defaultValue;
+    return {defaultValue.begin(), defaultValue.end()};
   }
-  return value->GetBooleanArray();
+  auto arr = value->GetBooleanArray();
+  return {arr.begin(), arr.end()};
 }
 
 inline std::vector<int> NetworkTableEntry::GetBooleanArray(
     std::initializer_list<int> defaultValue) const {
-  return GetBooleanArray(
-      wpi::makeArrayRef(defaultValue.begin(), defaultValue.end()));
+  return GetBooleanArray({defaultValue.begin(), defaultValue.end()});
 }
 
 inline std::vector<double> NetworkTableEntry::GetDoubleArray(
-    wpi::ArrayRef<double> defaultValue) const {
+    wpi::span<const double> defaultValue) const {
   auto value = GetEntryValue(m_handle);
   if (!value || value->type() != NT_DOUBLE_ARRAY) {
-    return defaultValue;
+    return {defaultValue.begin(), defaultValue.end()};
   }
-  return value->GetDoubleArray();
+  auto arr = value->GetDoubleArray();
+  return {arr.begin(), arr.end()};
 }
 
 inline std::vector<double> NetworkTableEntry::GetDoubleArray(
     std::initializer_list<double> defaultValue) const {
-  return GetDoubleArray(
-      wpi::makeArrayRef(defaultValue.begin(), defaultValue.end()));
+  return GetDoubleArray({defaultValue.begin(), defaultValue.end()});
 }
 
 inline std::vector<std::string> NetworkTableEntry::GetStringArray(
-    wpi::ArrayRef<std::string> defaultValue) const {
+    wpi::span<const std::string> defaultValue) const {
   auto value = GetEntryValue(m_handle);
   if (!value || value->type() != NT_STRING_ARRAY) {
-    return defaultValue;
+    return {defaultValue.begin(), defaultValue.end()};
   }
-  return value->GetStringArray();
+  auto arr = value->GetStringArray();
+  return {arr.begin(), arr.end()};
 }
 
 inline std::vector<std::string> NetworkTableEntry::GetStringArray(
     std::initializer_list<std::string> defaultValue) const {
-  return GetStringArray(
-      wpi::makeArrayRef(defaultValue.begin(), defaultValue.end()));
+  return GetStringArray({defaultValue.begin(), defaultValue.end()});
 }
 
 inline bool NetworkTableEntry::SetDefaultValue(std::shared_ptr<Value> value) {
@@ -151,7 +151,7 @@ inline bool NetworkTableEntry::SetDefaultRaw(std::string_view defaultValue) {
 }
 
 inline bool NetworkTableEntry::SetDefaultBooleanArray(
-    wpi::ArrayRef<int> defaultValue) {
+    wpi::span<const int> defaultValue) {
   return SetDefaultEntryValue(m_handle, Value::MakeBooleanArray(defaultValue));
 }
 
@@ -161,7 +161,7 @@ inline bool NetworkTableEntry::SetDefaultBooleanArray(
 }
 
 inline bool NetworkTableEntry::SetDefaultDoubleArray(
-    wpi::ArrayRef<double> defaultValue) {
+    wpi::span<const double> defaultValue) {
   return SetDefaultEntryValue(m_handle, Value::MakeDoubleArray(defaultValue));
 }
 
@@ -171,7 +171,7 @@ inline bool NetworkTableEntry::SetDefaultDoubleArray(
 }
 
 inline bool NetworkTableEntry::SetDefaultStringArray(
-    wpi::ArrayRef<std::string> defaultValue) {
+    wpi::span<const std::string> defaultValue) {
   return SetDefaultEntryValue(m_handle, Value::MakeStringArray(defaultValue));
 }
 
@@ -200,7 +200,7 @@ inline bool NetworkTableEntry::SetRaw(std::string_view value) {
   return SetEntryValue(m_handle, Value::MakeRaw(value));
 }
 
-inline bool NetworkTableEntry::SetBooleanArray(wpi::ArrayRef<bool> value) {
+inline bool NetworkTableEntry::SetBooleanArray(wpi::span<const bool> value) {
   return SetEntryValue(m_handle, Value::MakeBooleanArray(value));
 }
 
@@ -209,7 +209,7 @@ inline bool NetworkTableEntry::SetBooleanArray(
   return SetEntryValue(m_handle, Value::MakeBooleanArray(value));
 }
 
-inline bool NetworkTableEntry::SetBooleanArray(wpi::ArrayRef<int> value) {
+inline bool NetworkTableEntry::SetBooleanArray(wpi::span<const int> value) {
   return SetEntryValue(m_handle, Value::MakeBooleanArray(value));
 }
 
@@ -218,7 +218,7 @@ inline bool NetworkTableEntry::SetBooleanArray(
   return SetEntryValue(m_handle, Value::MakeBooleanArray(value));
 }
 
-inline bool NetworkTableEntry::SetDoubleArray(wpi::ArrayRef<double> value) {
+inline bool NetworkTableEntry::SetDoubleArray(wpi::span<const double> value) {
   return SetEntryValue(m_handle, Value::MakeDoubleArray(value));
 }
 
@@ -228,7 +228,7 @@ inline bool NetworkTableEntry::SetDoubleArray(
 }
 
 inline bool NetworkTableEntry::SetStringArray(
-    wpi::ArrayRef<std::string> value) {
+    wpi::span<const std::string> value) {
   return SetEntryValue(m_handle, Value::MakeStringArray(value));
 }
 
@@ -257,7 +257,8 @@ inline void NetworkTableEntry::ForceSetRaw(std::string_view value) {
   SetEntryTypeValue(m_handle, Value::MakeRaw(value));
 }
 
-inline void NetworkTableEntry::ForceSetBooleanArray(wpi::ArrayRef<bool> value) {
+inline void NetworkTableEntry::ForceSetBooleanArray(
+    wpi::span<const bool> value) {
   SetEntryTypeValue(m_handle, Value::MakeBooleanArray(value));
 }
 
@@ -266,7 +267,8 @@ inline void NetworkTableEntry::ForceSetBooleanArray(
   SetEntryTypeValue(m_handle, Value::MakeBooleanArray(value));
 }
 
-inline void NetworkTableEntry::ForceSetBooleanArray(wpi::ArrayRef<int> value) {
+inline void NetworkTableEntry::ForceSetBooleanArray(
+    wpi::span<const int> value) {
   SetEntryTypeValue(m_handle, Value::MakeBooleanArray(value));
 }
 
@@ -276,7 +278,7 @@ inline void NetworkTableEntry::ForceSetBooleanArray(
 }
 
 inline void NetworkTableEntry::ForceSetDoubleArray(
-    wpi::ArrayRef<double> value) {
+    wpi::span<const double> value) {
   SetEntryTypeValue(m_handle, Value::MakeDoubleArray(value));
 }
 
@@ -286,7 +288,7 @@ inline void NetworkTableEntry::ForceSetDoubleArray(
 }
 
 inline void NetworkTableEntry::ForceSetStringArray(
-    wpi::ArrayRef<std::string> value) {
+    wpi::span<const std::string> value) {
   SetEntryTypeValue(m_handle, Value::MakeStringArray(value));
 }
 
diff --git a/ntcore/src/main/native/include/networktables/NetworkTableInstance.h b/ntcore/src/main/native/include/networktables/NetworkTableInstance.h
index 3f7f247ac7..f91efa0857 100644
--- a/ntcore/src/main/native/include/networktables/NetworkTableInstance.h
+++ b/ntcore/src/main/native/include/networktables/NetworkTableInstance.h
@@ -12,7 +12,7 @@
 #include <utility>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "networktables/NetworkTable.h"
 #include "networktables/NetworkTableEntry.h"
@@ -342,7 +342,7 @@ class NetworkTableInstance final {
    * @param servers   array of server name and port pairs
    */
   void StartClient(
-      wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers);
+      wpi::span<const std::pair<std::string_view, unsigned int>> servers);
 
   /**
    * Starts a client using the specified servers and port.  The
@@ -351,7 +351,7 @@ class NetworkTableInstance final {
    * @param servers   array of server names
    * @param port      port to communicate over
    */
-  void StartClient(wpi::ArrayRef<std::string_view> servers,
+  void StartClient(wpi::span<const std::string_view> servers,
                    unsigned int port = kDefaultPort);
 
   /**
@@ -383,7 +383,7 @@ class NetworkTableInstance final {
    * @param servers   array of server name and port pairs
    */
   void SetServer(
-      wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers);
+      wpi::span<const std::pair<std::string_view, unsigned int>> servers);
 
   /**
    * Sets server addresses and port for client (without restarting client).
@@ -392,7 +392,7 @@ class NetworkTableInstance final {
    * @param servers   array of server names
    * @param port      port to communicate over
    */
-  void SetServer(wpi::ArrayRef<std::string_view> servers,
+  void SetServer(wpi::span<const std::string_view> servers,
                  unsigned int port = kDefaultPort);
 
   /**
diff --git a/ntcore/src/main/native/include/networktables/NetworkTableInstance.inc b/ntcore/src/main/native/include/networktables/NetworkTableInstance.inc
index 9bb5399d8a..5cb7be0aac 100644
--- a/ntcore/src/main/native/include/networktables/NetworkTableInstance.inc
+++ b/ntcore/src/main/native/include/networktables/NetworkTableInstance.inc
@@ -117,7 +117,7 @@ inline void NetworkTableInstance::StartClient(const char* server_name,
 }
 
 inline void NetworkTableInstance::StartClient(
-    wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers) {
+    wpi::span<const std::pair<std::string_view, unsigned int>> servers) {
   ::nt::StartClient(m_handle, servers);
 }
 
@@ -136,7 +136,7 @@ inline void NetworkTableInstance::SetServer(const char* server_name,
 }
 
 inline void NetworkTableInstance::SetServer(
-    wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers) {
+    wpi::span<const std::pair<std::string_view, unsigned int>> servers) {
   ::nt::SetServer(m_handle, servers);
 }
 
diff --git a/ntcore/src/main/native/include/networktables/NetworkTableValue.h b/ntcore/src/main/native/include/networktables/NetworkTableValue.h
index acc51ad2b9..c8f73a19f3 100644
--- a/ntcore/src/main/native/include/networktables/NetworkTableValue.h
+++ b/ntcore/src/main/native/include/networktables/NetworkTableValue.h
@@ -16,7 +16,7 @@
 #include <utility>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "ntcore_c.h"
 
@@ -192,10 +192,9 @@ class Value final {
    *
    * @return The boolean array value.
    */
-  wpi::ArrayRef<int> GetBooleanArray() const {
+  wpi::span<const int> GetBooleanArray() const {
     assert(m_val.type == NT_BOOLEAN_ARRAY);
-    return wpi::ArrayRef<int>(m_val.data.arr_boolean.arr,
-                              m_val.data.arr_boolean.size);
+    return {m_val.data.arr_boolean.arr, m_val.data.arr_boolean.size};
   }
 
   /**
@@ -203,10 +202,9 @@ class Value final {
    *
    * @return The double array value.
    */
-  wpi::ArrayRef<double> GetDoubleArray() const {
+  wpi::span<const double> GetDoubleArray() const {
     assert(m_val.type == NT_DOUBLE_ARRAY);
-    return wpi::ArrayRef<double>(m_val.data.arr_double.arr,
-                                 m_val.data.arr_double.size);
+    return {m_val.data.arr_double.arr, m_val.data.arr_double.size};
   }
 
   /**
@@ -214,7 +212,7 @@ class Value final {
    *
    * @return The string array value.
    */
-  wpi::ArrayRef<std::string> GetStringArray() const {
+  wpi::span<const std::string> GetStringArray() const {
     assert(m_val.type == NT_STRING_ARRAY);
     return m_string_array;
   }
@@ -366,7 +364,7 @@ class Value final {
    *             time)
    * @return The entry value
    */
-  static std::shared_ptr<Value> MakeBooleanArray(wpi::ArrayRef<bool> value,
+  static std::shared_ptr<Value> MakeBooleanArray(wpi::span<const bool> value,
                                                  uint64_t time = 0);
 
   /**
@@ -379,8 +377,7 @@ class Value final {
    */
   static std::shared_ptr<Value> MakeBooleanArray(
       std::initializer_list<bool> value, uint64_t time = 0) {
-    return MakeBooleanArray(wpi::makeArrayRef(value.begin(), value.end()),
-                            time);
+    return MakeBooleanArray(wpi::span(value.begin(), value.end()), time);
   }
 
   /**
@@ -391,7 +388,7 @@ class Value final {
    *             time)
    * @return The entry value
    */
-  static std::shared_ptr<Value> MakeBooleanArray(wpi::ArrayRef<int> value,
+  static std::shared_ptr<Value> MakeBooleanArray(wpi::span<const int> value,
                                                  uint64_t time = 0);
 
   /**
@@ -404,8 +401,7 @@ class Value final {
    */
   static std::shared_ptr<Value> MakeBooleanArray(
       std::initializer_list<int> value, uint64_t time = 0) {
-    return MakeBooleanArray(wpi::makeArrayRef(value.begin(), value.end()),
-                            time);
+    return MakeBooleanArray(wpi::span(value.begin(), value.end()), time);
   }
 
   /**
@@ -416,7 +412,7 @@ class Value final {
    *             time)
    * @return The entry value
    */
-  static std::shared_ptr<Value> MakeDoubleArray(wpi::ArrayRef<double> value,
+  static std::shared_ptr<Value> MakeDoubleArray(wpi::span<const double> value,
                                                 uint64_t time = 0);
 
   /**
@@ -429,7 +425,7 @@ class Value final {
    */
   static std::shared_ptr<Value> MakeDoubleArray(
       std::initializer_list<double> value, uint64_t time = 0) {
-    return MakeDoubleArray(wpi::makeArrayRef(value.begin(), value.end()), time);
+    return MakeDoubleArray(wpi::span(value.begin(), value.end()), time);
   }
 
   /**
@@ -441,7 +437,7 @@ class Value final {
    * @return The entry value
    */
   static std::shared_ptr<Value> MakeStringArray(
-      wpi::ArrayRef<std::string> value, uint64_t time = 0);
+      wpi::span<const std::string> value, uint64_t time = 0);
 
   /**
    * Creates a string array entry value.
@@ -453,7 +449,7 @@ class Value final {
    */
   static std::shared_ptr<Value> MakeStringArray(
       std::initializer_list<std::string> value, uint64_t time = 0) {
-    return MakeStringArray(wpi::makeArrayRef(value.begin(), value.end()), time);
+    return MakeStringArray(wpi::span(value.begin(), value.end()), time);
   }
 
   /**
diff --git a/ntcore/src/main/native/include/ntcore_cpp.h b/ntcore/src/main/native/include/ntcore_cpp.h
index 2bc517a6d7..8126b80942 100644
--- a/ntcore/src/main/native/include/ntcore_cpp.h
+++ b/ntcore/src/main/native/include/ntcore_cpp.h
@@ -16,7 +16,7 @@
 #include <utility>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "networktables/NetworkTableValue.h"
 
@@ -955,7 +955,7 @@ bool UnpackRpcDefinition(std::string_view packed, RpcDefinition* def);
  * @param values      array of values to pack
  * @return Raw packed bytes.
  */
-std::string PackRpcValues(wpi::ArrayRef<std::shared_ptr<Value>> values);
+std::string PackRpcValues(wpi::span<const std::shared_ptr<Value>> values);
 
 /**
  * Unpack RPC values as required for RPC version 1 definition messages.
@@ -965,7 +965,7 @@ std::string PackRpcValues(wpi::ArrayRef<std::shared_ptr<Value>> values);
  * @return Array of values.
  */
 std::vector<std::shared_ptr<Value>> UnpackRpcValues(
-    std::string_view packed, wpi::ArrayRef<NT_Type> types);
+    std::string_view packed, wpi::span<const NT_Type> types);
 
 /** @} */
 
@@ -1050,7 +1050,7 @@ void StartClient(NT_Inst inst, const char* server_name, unsigned int port);
  */
 void StartClient(
     NT_Inst inst,
-    wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers);
+    wpi::span<const std::pair<std::string_view, unsigned int>> servers);
 
 /**
  * Starts a client using commonly known robot addresses for the specified
@@ -1087,7 +1087,7 @@ void SetServer(NT_Inst inst, const char* server_name, unsigned int port);
  */
 void SetServer(
     NT_Inst inst,
-    wpi::ArrayRef<std::pair<std::string_view, unsigned int>> servers);
+    wpi::span<const std::pair<std::string_view, unsigned int>> servers);
 
 /**
  * Sets server addresses and port for client (without restarting client).
diff --git a/ntcore/src/test/native/cpp/ValueTest.cpp b/ntcore/src/test/native/cpp/ValueTest.cpp
index 271f7b67ae..d28611cd56 100644
--- a/ntcore/src/test/native/cpp/ValueTest.cpp
+++ b/ntcore/src/test/native/cpp/ValueTest.cpp
@@ -2,6 +2,7 @@
 // Open Source Software; you can modify and/or share it under the terms of
 // the WPILib BSD license file in the root directory of this project.
 
+#include <algorithm>
 #include <string_view>
 
 #include "TestPrinters.h"
@@ -11,6 +12,16 @@
 
 using namespace std::string_view_literals;
 
+namespace wpi {
+template <typename T>
+inline bool operator==(span<T> lhs, span<T> rhs) {
+  if (lhs.size() != rhs.size()) {
+    return false;
+  }
+  return std::equal(lhs.begin(), lhs.end(), rhs.begin());
+}
+}  // namespace wpi
+
 namespace nt {
 
 class ValueTest : public ::testing::Test {};
@@ -110,7 +121,7 @@ TEST_F(ValueTest, BooleanArray) {
   std::vector<int> vec{1, 0, 1};
   auto v = Value::MakeBooleanArray(vec);
   ASSERT_EQ(NT_BOOLEAN_ARRAY, v->type());
-  ASSERT_EQ(wpi::ArrayRef<int>(vec), v->GetBooleanArray());
+  ASSERT_EQ(wpi::span<const int>(vec), v->GetBooleanArray());
   NT_Value cv;
   NT_InitValue(&cv);
   ConvertToC(*v, &cv);
@@ -124,7 +135,7 @@ TEST_F(ValueTest, BooleanArray) {
   vec = {0, 1, 0};
   v = Value::MakeBooleanArray(vec);
   ASSERT_EQ(NT_BOOLEAN_ARRAY, v->type());
-  ASSERT_EQ(wpi::ArrayRef<int>(vec), v->GetBooleanArray());
+  ASSERT_EQ(wpi::span<const int>(vec), v->GetBooleanArray());
   ConvertToC(*v, &cv);
   ASSERT_EQ(NT_BOOLEAN_ARRAY, cv.type);
   ASSERT_EQ(3u, cv.data.arr_boolean.size);
@@ -136,7 +147,7 @@ TEST_F(ValueTest, BooleanArray) {
   vec = {1, 0};
   v = Value::MakeBooleanArray(vec);
   ASSERT_EQ(NT_BOOLEAN_ARRAY, v->type());
-  ASSERT_EQ(wpi::ArrayRef<int>(vec), v->GetBooleanArray());
+  ASSERT_EQ(wpi::span<const int>(vec), v->GetBooleanArray());
   ConvertToC(*v, &cv);
   ASSERT_EQ(NT_BOOLEAN_ARRAY, cv.type);
   ASSERT_EQ(2u, cv.data.arr_boolean.size);
@@ -150,7 +161,7 @@ TEST_F(ValueTest, DoubleArray) {
   std::vector<double> vec{0.5, 0.25, 0.5};
   auto v = Value::MakeDoubleArray(vec);
   ASSERT_EQ(NT_DOUBLE_ARRAY, v->type());
-  ASSERT_EQ(wpi::ArrayRef<double>(vec), v->GetDoubleArray());
+  ASSERT_EQ(wpi::span<const double>(vec), v->GetDoubleArray());
   NT_Value cv;
   NT_InitValue(&cv);
   ConvertToC(*v, &cv);
@@ -164,7 +175,7 @@ TEST_F(ValueTest, DoubleArray) {
   vec = {0.25, 0.5, 0.25};
   v = Value::MakeDoubleArray(vec);
   ASSERT_EQ(NT_DOUBLE_ARRAY, v->type());
-  ASSERT_EQ(wpi::ArrayRef<double>(vec), v->GetDoubleArray());
+  ASSERT_EQ(wpi::span<const double>(vec), v->GetDoubleArray());
   ConvertToC(*v, &cv);
   ASSERT_EQ(NT_DOUBLE_ARRAY, cv.type);
   ASSERT_EQ(3u, cv.data.arr_double.size);
@@ -176,7 +187,7 @@ TEST_F(ValueTest, DoubleArray) {
   vec = {0.5, 0.25};
   v = Value::MakeDoubleArray(vec);
   ASSERT_EQ(NT_DOUBLE_ARRAY, v->type());
-  ASSERT_EQ(wpi::ArrayRef<double>(vec), v->GetDoubleArray());
+  ASSERT_EQ(wpi::span<const double>(vec), v->GetDoubleArray());
   ConvertToC(*v, &cv);
   ASSERT_EQ(NT_DOUBLE_ARRAY, cv.type);
   ASSERT_EQ(2u, cv.data.arr_double.size);
diff --git a/simulation/halsim_ds_socket/src/main/native/cpp/DSCommPacket.cpp b/simulation/halsim_ds_socket/src/main/native/cpp/DSCommPacket.cpp
index aeaf5e1101..9088bd7ee8 100644
--- a/simulation/halsim_ds_socket/src/main/native/cpp/DSCommPacket.cpp
+++ b/simulation/halsim_ds_socket/src/main/native/cpp/DSCommPacket.cpp
@@ -12,7 +12,7 @@
 
 #include <hal/simulation/DriverStationData.h>
 #include <hal/simulation/MockHooks.h>
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 using namespace halsim;
 
@@ -45,7 +45,7 @@ void DSCommPacket::SetAlliance(uint8_t station_code) {
   m_alliance_station = static_cast<HAL_AllianceStationID>(station_code);
 }
 
-void DSCommPacket::ReadMatchtimeTag(wpi::ArrayRef<uint8_t> tagData) {
+void DSCommPacket::ReadMatchtimeTag(wpi::span<const uint8_t> tagData) {
   if (tagData.size() < 6) {
     return;
   }
@@ -63,7 +63,7 @@ void DSCommPacket::ReadMatchtimeTag(wpi::ArrayRef<uint8_t> tagData) {
   m_match_time = matchTime;
 }
 
-void DSCommPacket::ReadJoystickTag(wpi::ArrayRef<uint8_t> dataInput,
+void DSCommPacket::ReadJoystickTag(wpi::span<const uint8_t> dataInput,
                                    int index) {
   DSCommJoystickPacket& stick = m_joystick_packets[index];
   stick.ResetUdp();
@@ -72,7 +72,7 @@ void DSCommPacket::ReadJoystickTag(wpi::ArrayRef<uint8_t> dataInput,
     return;
   }
 
-  dataInput = dataInput.slice(2);
+  dataInput = dataInput.subspan(2);
 
   // Read axes
   int axesLength = dataInput[0];
@@ -86,7 +86,7 @@ void DSCommPacket::ReadJoystickTag(wpi::ArrayRef<uint8_t> dataInput,
   }
   stick.axes.count = axesLength;
 
-  dataInput = dataInput.slice(1 + axesLength);
+  dataInput = dataInput.subspan(1 + axesLength);
 
   // Read Buttons
   int buttonCount = dataInput[0];
@@ -97,7 +97,7 @@ void DSCommPacket::ReadJoystickTag(wpi::ArrayRef<uint8_t> dataInput,
   }
   stick.buttons.count = buttonCount;
 
-  dataInput = dataInput.slice(1 + numBytes);
+  dataInput = dataInput.subspan(1 + numBytes);
 
   int povsLength = dataInput[0];
   for (int i = 0; i < povsLength * 2; i += 2) {
@@ -112,11 +112,11 @@ void DSCommPacket::ReadJoystickTag(wpi::ArrayRef<uint8_t> dataInput,
 /*----------------------------------------------------------------------------
 **  Communication methods
 **--------------------------------------------------------------------------*/
-void DSCommPacket::DecodeTCP(wpi::ArrayRef<uint8_t> packet) {
+void DSCommPacket::DecodeTCP(wpi::span<const uint8_t> packet) {
   // No header
   while (!packet.empty()) {
     int tagLength = packet[0] << 8 | packet[1];
-    auto tagPacket = packet.slice(0, tagLength + 2);
+    auto tagPacket = packet.subspan(0, tagLength + 2);
 
     if (tagLength == 0) {
       return;
@@ -133,11 +133,11 @@ void DSCommPacket::DecodeTCP(wpi::ArrayRef<uint8_t> packet) {
         ReadNewMatchInfoTag(tagPacket);
         break;
     }
-    packet = packet.slice(tagLength + 2);
+    packet = packet.subspan(tagLength + 2);
   }
 }
 
-void DSCommPacket::DecodeUDP(wpi::ArrayRef<uint8_t> packet) {
+void DSCommPacket::DecodeUDP(wpi::span<const uint8_t> packet) {
   if (packet.size() < 6) {
     return;
   }
@@ -154,14 +154,14 @@ void DSCommPacket::DecodeUDP(wpi::ArrayRef<uint8_t> packet) {
   }
 
   // Else, handle tagged data
-  packet = packet.slice(6);
+  packet = packet.subspan(6);
 
   int joystickNum = 0;
 
   // Loop to handle multiple tags
   while (!packet.empty()) {
     auto tagLength = packet[0];
-    auto tagPacket = packet.slice(0, tagLength + 1);
+    auto tagPacket = packet.subspan(0, tagLength + 1);
 
     switch (packet[1]) {
       case kJoystickDataTag:
@@ -172,11 +172,11 @@ void DSCommPacket::DecodeUDP(wpi::ArrayRef<uint8_t> packet) {
         ReadMatchtimeTag(tagPacket);
         break;
     }
-    packet = packet.slice(tagLength + 1);
+    packet = packet.subspan(tagLength + 1);
   }
 }
 
-void DSCommPacket::ReadNewMatchInfoTag(wpi::ArrayRef<uint8_t> data) {
+void DSCommPacket::ReadNewMatchInfoTag(wpi::span<const uint8_t> data) {
   // Size 2 bytes, tag 1 byte
   if (data.size() <= 3) {
     return;
@@ -190,7 +190,7 @@ void DSCommPacket::ReadNewMatchInfoTag(wpi::ArrayRef<uint8_t> data) {
 
   matchInfo.eventName[nameLength] = '\0';
 
-  data = data.slice(4 + nameLength);
+  data = data.subspan(4 + nameLength);
 
   if (data.size() < 4) {
     return;
@@ -204,7 +204,7 @@ void DSCommPacket::ReadNewMatchInfoTag(wpi::ArrayRef<uint8_t> data) {
   HALSIM_SetMatchInfo(&matchInfo);
 }
 
-void DSCommPacket::ReadGameSpecificMessageTag(wpi::ArrayRef<uint8_t> data) {
+void DSCommPacket::ReadGameSpecificMessageTag(wpi::span<const uint8_t> data) {
   // Size 2 bytes, tag 1 byte
   if (data.size() <= 3) {
     return;
@@ -220,11 +220,11 @@ void DSCommPacket::ReadGameSpecificMessageTag(wpi::ArrayRef<uint8_t> data) {
 
   HALSIM_SetMatchInfo(&matchInfo);
 }
-void DSCommPacket::ReadJoystickDescriptionTag(wpi::ArrayRef<uint8_t> data) {
+void DSCommPacket::ReadJoystickDescriptionTag(wpi::span<const uint8_t> data) {
   if (data.size() < 3) {
     return;
   }
-  data = data.slice(3);
+  data = data.subspan(3);
   int joystickNum = data[0];
   DSCommJoystickPacket& packet = m_joystick_packets[joystickNum];
   packet.ResetTcp();
@@ -235,14 +235,14 @@ void DSCommPacket::ReadJoystickDescriptionTag(wpi::ArrayRef<uint8_t> data) {
   for (int i = 0; i < nameLength; i++) {
     packet.descriptor.name[i] = data[4 + i];
   }
-  data = data.slice(4 + nameLength);
+  data = data.subspan(4 + nameLength);
   packet.descriptor.name[nameLength] = '\0';
   int axesCount = data[0];
   packet.descriptor.axisCount = axesCount;
   for (int i = 0; i < axesCount; i++) {
     packet.descriptor.axisTypes[i] = data[1 + i];
   }
-  data = data.slice(1 + axesCount);
+  data = data.subspan(1 + axesCount);
 
   packet.descriptor.buttonCount = data[0];
   packet.descriptor.povCount = data[1];
diff --git a/simulation/halsim_ds_socket/src/main/native/cpp/main.cpp b/simulation/halsim_ds_socket/src/main/native/cpp/main.cpp
index c9fa585334..799cdd9f95 100644
--- a/simulation/halsim_ds_socket/src/main/native/cpp/main.cpp
+++ b/simulation/halsim_ds_socket/src/main/native/cpp/main.cpp
@@ -116,13 +116,12 @@ static void SetupUdp(wpi::uv::Loop& loop) {
   struct sockaddr_in simAddr;
   NameToAddr("127.0.0.1", 1135, &simAddr);
   simLoopTimer->timeout.connect([udpLocal = udp.get(), simAddr] {
-    udpLocal->Send(simAddr, wpi::ArrayRef<Buffer>{singleByte.get(), 1},
-                   [](auto buf, Error err) {
-                     if (err) {
-                       fmt::print(stderr, "{}\n", err.str());
-                       std::fflush(stderr);
-                     }
-                   });
+    udpLocal->Send(simAddr, {singleByte.get(), 1}, [](auto buf, Error err) {
+      if (err) {
+        fmt::print(stderr, "{}\n", err.str());
+        std::fflush(stderr);
+      }
+    });
   });
   simLoopTimer->Start(Timer::Time{100}, Timer::Time{100});
 
@@ -131,8 +130,7 @@ static void SetupUdp(wpi::uv::Loop& loop) {
                                                const sockaddr& recSock,
                                                unsigned int port) {
     auto ds = udpLocal->GetLoop()->GetData<halsim::DSCommPacket>();
-    ds->DecodeUDP(
-        wpi::ArrayRef<uint8_t>{reinterpret_cast<uint8_t*>(buf.base), len});
+    ds->DecodeUDP({reinterpret_cast<uint8_t*>(buf.base), len});
 
     struct sockaddr_in outAddr;
     std::memcpy(&outAddr, &recSock, sizeof(sockaddr_in));
diff --git a/simulation/halsim_ds_socket/src/main/native/include/DSCommPacket.h b/simulation/halsim_ds_socket/src/main/native/include/DSCommPacket.h
index 66b341961d..1285711bfe 100644
--- a/simulation/halsim_ds_socket/src/main/native/include/DSCommPacket.h
+++ b/simulation/halsim_ds_socket/src/main/native/include/DSCommPacket.h
@@ -8,8 +8,8 @@
 
 #include <DSCommJoystickPacket.h>
 #include <hal/simulation/DriverStationData.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/raw_uv_ostream.h>
+#include <wpi/span.h>
 
 class DSCommPacketTest;
 
@@ -20,8 +20,8 @@ class DSCommPacket {
 
  public:
   DSCommPacket(void);
-  void DecodeTCP(wpi::ArrayRef<uint8_t> packet);
-  void DecodeUDP(wpi::ArrayRef<uint8_t> packet);
+  void DecodeTCP(wpi::span<const uint8_t> packet);
+  void DecodeUDP(wpi::span<const uint8_t> packet);
   void SendUDPToHALSim(void);
   void SetupSendBuffer(wpi::raw_uv_ostream& buf);
 
@@ -53,11 +53,11 @@ class DSCommPacket {
   void SetAlliance(uint8_t station_code);
   void SetupSendHeader(wpi::raw_uv_ostream& buf);
   void SetupJoystickTag(wpi::raw_uv_ostream& buf);
-  void ReadMatchtimeTag(wpi::ArrayRef<uint8_t> tagData);
-  void ReadJoystickTag(wpi::ArrayRef<uint8_t> data, int index);
-  void ReadNewMatchInfoTag(wpi::ArrayRef<uint8_t> data);
-  void ReadGameSpecificMessageTag(wpi::ArrayRef<uint8_t> data);
-  void ReadJoystickDescriptionTag(wpi::ArrayRef<uint8_t> data);
+  void ReadMatchtimeTag(wpi::span<const uint8_t> tagData);
+  void ReadJoystickTag(wpi::span<const uint8_t> data, int index);
+  void ReadNewMatchInfoTag(wpi::span<const uint8_t> data);
+  void ReadGameSpecificMessageTag(wpi::span<const uint8_t> data);
+  void ReadJoystickDescriptionTag(wpi::span<const uint8_t> data);
 
   uint8_t m_hi;
   uint8_t m_lo;
diff --git a/simulation/halsim_ds_socket/src/test/native/cpp/DSCommPacketTest.cpp b/simulation/halsim_ds_socket/src/test/native/cpp/DSCommPacketTest.cpp
index 1425ac082d..84df27cc17 100644
--- a/simulation/halsim_ds_socket/src/test/native/cpp/DSCommPacketTest.cpp
+++ b/simulation/halsim_ds_socket/src/test/native/cpp/DSCommPacketTest.cpp
@@ -11,23 +11,24 @@ class DSCommPacketTest : public ::testing::Test {
 
   void SendJoysticks() { commPacket.SendJoysticks(); }
 
-  halsim::DSCommJoystickPacket& ReadJoystickTag(wpi::ArrayRef<uint8_t> data,
+  halsim::DSCommJoystickPacket& ReadJoystickTag(wpi::span<const uint8_t> data,
                                                 int index) {
     commPacket.ReadJoystickTag(data, index);
     return commPacket.m_joystick_packets[index];
   }
 
-  halsim::DSCommJoystickPacket& ReadDescriptorTag(wpi::ArrayRef<uint8_t> data) {
+  halsim::DSCommJoystickPacket& ReadDescriptorTag(
+      wpi::span<const uint8_t> data) {
     commPacket.ReadJoystickDescriptionTag(data);
     return commPacket.m_joystick_packets[data[3]];
   }
 
-  HAL_MatchInfo& ReadNewMatchInfoTag(wpi::ArrayRef<uint8_t> data) {
+  HAL_MatchInfo& ReadNewMatchInfoTag(wpi::span<const uint8_t> data) {
     commPacket.ReadNewMatchInfoTag(data);
     return commPacket.matchInfo;
   }
 
-  HAL_MatchInfo& ReadGameSpecificTag(wpi::ArrayRef<uint8_t> data) {
+  HAL_MatchInfo& ReadGameSpecificTag(wpi::span<const uint8_t> data) {
     commPacket.ReadGameSpecificMessageTag(data);
     return commPacket.matchInfo;
   }
diff --git a/simulation/halsim_gui/src/main/native/cpp/AddressableLEDGui.cpp b/simulation/halsim_gui/src/main/native/cpp/AddressableLEDGui.cpp
index 586bbd8841..23a52381f2 100644
--- a/simulation/halsim_gui/src/main/native/cpp/AddressableLEDGui.cpp
+++ b/simulation/halsim_gui/src/main/native/cpp/AddressableLEDGui.cpp
@@ -26,7 +26,7 @@ class AddressableLEDModel : public glass::LEDDisplayModel {
 
   bool IsRunning() override { return HALSIM_GetAddressableLEDRunning(m_index); }
 
-  wpi::ArrayRef<Data> GetData(wpi::SmallVectorImpl<Data>&) override {
+  wpi::span<const Data> GetData(wpi::SmallVectorImpl<Data>&) override {
     size_t length = HALSIM_GetAddressableLEDData(m_index, m_data);
     return {reinterpret_cast<Data*>(m_data), length};
   }
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/Command.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/Command.cpp
index 2abd7c0dd8..b434c1be05 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/Command.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/Command.cpp
@@ -48,12 +48,11 @@ SequentialCommandGroup Command::BeforeStarting(
     std::function<void()> toRun,
     std::initializer_list<Subsystem*> requirements) && {
   return std::move(*this).BeforeStarting(
-      std::move(toRun),
-      wpi::makeArrayRef(requirements.begin(), requirements.end()));
+      std::move(toRun), {requirements.begin(), requirements.end()});
 }
 
 SequentialCommandGroup Command::BeforeStarting(
-    std::function<void()> toRun, wpi::ArrayRef<Subsystem*> requirements) && {
+    std::function<void()> toRun, wpi::span<Subsystem* const> requirements) && {
   std::vector<std::unique_ptr<Command>> temp;
   temp.emplace_back(
       std::make_unique<InstantCommand>(std::move(toRun), requirements));
@@ -64,13 +63,12 @@ SequentialCommandGroup Command::BeforeStarting(
 SequentialCommandGroup Command::AndThen(
     std::function<void()> toRun,
     std::initializer_list<Subsystem*> requirements) && {
-  return std::move(*this).AndThen(
-      std::move(toRun),
-      wpi::makeArrayRef(requirements.begin(), requirements.end()));
+  return std::move(*this).AndThen(std::move(toRun),
+                                  {requirements.begin(), requirements.end()});
 }
 
 SequentialCommandGroup Command::AndThen(
-    std::function<void()> toRun, wpi::ArrayRef<Subsystem*> requirements) && {
+    std::function<void()> toRun, wpi::span<Subsystem* const> requirements) && {
   std::vector<std::unique_ptr<Command>> temp;
   temp.emplace_back(std::move(*this).TransferOwnership());
   temp.emplace_back(
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandBase.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandBase.cpp
index 654ba58037..c1415a4282 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandBase.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandBase.cpp
@@ -18,7 +18,7 @@ void CommandBase::AddRequirements(
   m_requirements.insert(requirements.begin(), requirements.end());
 }
 
-void CommandBase::AddRequirements(wpi::ArrayRef<Subsystem*> requirements) {
+void CommandBase::AddRequirements(wpi::span<Subsystem* const> requirements) {
   m_requirements.insert(requirements.begin(), requirements.end());
 }
 
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandGroupBase.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandGroupBase.cpp
index d6c89aec1f..a3d275df42 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandGroupBase.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandGroupBase.cpp
@@ -6,7 +6,7 @@
 
 using namespace frc2;
 
-bool CommandGroupBase::RequireUngrouped(Command& command) {
+bool CommandGroupBase::RequireUngrouped(const Command& command) {
   if (command.IsGrouped()) {
     throw FRC_MakeError(
         frc::err::CommandIllegalUse, "{}",
@@ -15,8 +15,12 @@ bool CommandGroupBase::RequireUngrouped(Command& command) {
   return true;
 }
 
+bool CommandGroupBase::RequireUngrouped(const Command* command) {
+  return RequireUngrouped(*command);
+}
+
 bool CommandGroupBase::RequireUngrouped(
-    wpi::ArrayRef<std::unique_ptr<Command>> commands) {
+    wpi::span<const std::unique_ptr<Command>> commands) {
   bool allUngrouped = true;
   for (auto&& command : commands) {
     allUngrouped &= !command.get()->IsGrouped();
@@ -30,7 +34,7 @@ bool CommandGroupBase::RequireUngrouped(
 }
 
 bool CommandGroupBase::RequireUngrouped(
-    std::initializer_list<Command*> commands) {
+    std::initializer_list<const Command*> commands) {
   bool allUngrouped = true;
   for (auto&& command : commands) {
     allUngrouped &= !command->IsGrouped();
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandScheduler.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandScheduler.cpp
index f269698dfe..295134a76b 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandScheduler.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/CommandScheduler.cpp
@@ -161,7 +161,7 @@ void CommandScheduler::Schedule(Command* command) {
 }
 
 void CommandScheduler::Schedule(bool interruptible,
-                                wpi::ArrayRef<Command*> commands) {
+                                wpi::span<Command* const> commands) {
   for (auto command : commands) {
     Schedule(interruptible, command);
   }
@@ -174,7 +174,7 @@ void CommandScheduler::Schedule(bool interruptible,
   }
 }
 
-void CommandScheduler::Schedule(wpi::ArrayRef<Command*> commands) {
+void CommandScheduler::Schedule(wpi::span<Command* const> commands) {
   for (auto command : commands) {
     Schedule(true, command);
   }
@@ -284,7 +284,8 @@ void CommandScheduler::RegisterSubsystem(
   }
 }
 
-void CommandScheduler::RegisterSubsystem(wpi::ArrayRef<Subsystem*> subsystems) {
+void CommandScheduler::RegisterSubsystem(
+    wpi::span<Subsystem* const> subsystems) {
   for (auto* subsystem : subsystems) {
     RegisterSubsystem(subsystem);
   }
@@ -298,7 +299,7 @@ void CommandScheduler::UnregisterSubsystem(
 }
 
 void CommandScheduler::UnregisterSubsystem(
-    wpi::ArrayRef<Subsystem*> subsystems) {
+    wpi::span<Subsystem* const> subsystems) {
   for (auto* subsystem : subsystems) {
     UnregisterSubsystem(subsystem);
   }
@@ -340,7 +341,7 @@ void CommandScheduler::Cancel(Command* command) {
   }
 }
 
-void CommandScheduler::Cancel(wpi::ArrayRef<Command*> commands) {
+void CommandScheduler::Cancel(wpi::span<Command* const> commands) {
   for (auto command : commands) {
     Cancel(command);
   }
@@ -370,7 +371,7 @@ units::second_t CommandScheduler::TimeSinceScheduled(
   }
 }
 bool CommandScheduler::IsScheduled(
-    wpi::ArrayRef<const Command*> commands) const {
+    wpi::span<const Command* const> commands) const {
   for (auto command : commands) {
     if (!IsScheduled(command)) {
       return false;
@@ -444,8 +445,7 @@ void CommandScheduler::InitSendable(frc::SendableBuilder& builder) {
           m_impl->scheduledCommands.end()) {
         Cancel(command);
       }
-      nt::NetworkTableEntry(cancelEntry)
-          .SetDoubleArray(wpi::ArrayRef<double>{});
+      nt::NetworkTableEntry(cancelEntry).SetDoubleArray({});
     }
 
     wpi::SmallVector<std::string, 8> names;
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/FunctionalCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/FunctionalCommand.cpp
index ab0a3bbb28..0c45099d68 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/FunctionalCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/FunctionalCommand.cpp
@@ -21,7 +21,7 @@ FunctionalCommand::FunctionalCommand(std::function<void()> onInit,
                                      std::function<void()> onExecute,
                                      std::function<void(bool)> onEnd,
                                      std::function<bool()> isFinished,
-                                     wpi::ArrayRef<Subsystem*> requirements)
+                                     wpi::span<Subsystem* const> requirements)
     : m_onInit{std::move(onInit)},
       m_onExecute{std::move(onExecute)},
       m_onEnd{std::move(onEnd)},
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/InstantCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/InstantCommand.cpp
index b7a6ae7d86..1e9d173c9b 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/InstantCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/InstantCommand.cpp
@@ -13,7 +13,7 @@ InstantCommand::InstantCommand(std::function<void()> toRun,
 }
 
 InstantCommand::InstantCommand(std::function<void()> toRun,
-                               wpi::ArrayRef<Subsystem*> requirements)
+                               wpi::span<Subsystem* const> requirements)
     : m_toRun{std::move(toRun)} {
   AddRequirements(requirements);
 }
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/MecanumControllerCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/MecanumControllerCommand.cpp
index f5e1cc178c..b7a5dcbd59 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/MecanumControllerCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/MecanumControllerCommand.cpp
@@ -102,7 +102,7 @@ MecanumControllerCommand::MecanumControllerCommand(
     std::function<void(units::volt_t, units::volt_t, units::volt_t,
                        units::volt_t)>
         output,
-    wpi::ArrayRef<Subsystem*> requirements)
+    wpi::span<Subsystem* const> requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
       m_feedforward(feedforward),
@@ -139,7 +139,7 @@ MecanumControllerCommand::MecanumControllerCommand(
     std::function<void(units::volt_t, units::volt_t, units::volt_t,
                        units::volt_t)>
         output,
-    wpi::ArrayRef<Subsystem*> requirements)
+    wpi::span<Subsystem* const> requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
       m_feedforward(feedforward),
@@ -218,7 +218,7 @@ MecanumControllerCommand::MecanumControllerCommand(
     std::function<void(units::meters_per_second_t, units::meters_per_second_t,
                        units::meters_per_second_t, units::meters_per_second_t)>
         output,
-    wpi::ArrayRef<Subsystem*> requirements)
+    wpi::span<Subsystem* const> requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
       m_kinematics(kinematics),
@@ -239,7 +239,7 @@ MecanumControllerCommand::MecanumControllerCommand(
     std::function<void(units::meters_per_second_t, units::meters_per_second_t,
                        units::meters_per_second_t, units::meters_per_second_t)>
         output,
-    wpi::ArrayRef<Subsystem*> requirements)
+    wpi::span<Subsystem* const> requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
       m_kinematics(kinematics),
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/NotifierCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/NotifierCommand.cpp
index 6928a35094..37e5bc6ae4 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/NotifierCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/NotifierCommand.cpp
@@ -15,7 +15,7 @@ NotifierCommand::NotifierCommand(std::function<void()> toRun,
 
 NotifierCommand::NotifierCommand(std::function<void()> toRun,
                                  units::second_t period,
-                                 wpi::ArrayRef<Subsystem*> requirements)
+                                 wpi::span<Subsystem* const> requirements)
     : m_toRun(toRun), m_notifier{std::move(toRun)}, m_period{period} {
   AddRequirements(requirements);
 }
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/PIDCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/PIDCommand.cpp
index 5e13ee0d04..d11735aa71 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/PIDCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/PIDCommand.cpp
@@ -24,7 +24,7 @@ PIDCommand::PIDCommand(PIDController controller,
                        std::function<double()> measurementSource,
                        std::function<double()> setpointSource,
                        std::function<void(double)> useOutput,
-                       wpi::ArrayRef<Subsystem*> requirements)
+                       wpi::span<Subsystem* const> requirements)
     : m_controller{std::move(controller)},
       m_measurement{std::move(measurementSource)},
       m_setpoint{std::move(setpointSource)},
@@ -43,7 +43,7 @@ PIDCommand::PIDCommand(PIDController controller,
 PIDCommand::PIDCommand(PIDController controller,
                        std::function<double()> measurementSource,
                        double setpoint, std::function<void(double)> useOutput,
-                       wpi::ArrayRef<Subsystem*> requirements)
+                       wpi::span<Subsystem* const> requirements)
     : PIDCommand(
           controller, measurementSource, [setpoint] { return setpoint; },
           useOutput, requirements) {}
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/PerpetualCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/PerpetualCommand.cpp
index d0307d34ca..0c199f2d05 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/PerpetualCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/PerpetualCommand.cpp
@@ -7,7 +7,7 @@
 using namespace frc2;
 
 PerpetualCommand::PerpetualCommand(std::unique_ptr<Command>&& command) {
-  if (!CommandGroupBase::RequireUngrouped(command)) {
+  if (!CommandGroupBase::RequireUngrouped(*command)) {
     return;
   }
   m_command = std::move(command);
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/ProxyScheduleCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/ProxyScheduleCommand.cpp
index 52e34d0f4e..116ce3c112 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/ProxyScheduleCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/ProxyScheduleCommand.cpp
@@ -6,10 +6,15 @@
 
 using namespace frc2;
 
-ProxyScheduleCommand::ProxyScheduleCommand(wpi::ArrayRef<Command*> toSchedule) {
+ProxyScheduleCommand::ProxyScheduleCommand(
+    wpi::span<Command* const> toSchedule) {
   SetInsert(m_toSchedule, toSchedule);
 }
 
+ProxyScheduleCommand::ProxyScheduleCommand(Command* toSchedule) {
+  SetInsert(m_toSchedule, {&toSchedule, 1});
+}
+
 void ProxyScheduleCommand::Initialize() {
   for (auto* command : m_toSchedule) {
     command->Schedule();
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/RamseteCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/RamseteCommand.cpp
index c974e19f83..0c0b852419 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/RamseteCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/RamseteCommand.cpp
@@ -39,7 +39,7 @@ RamseteCommand::RamseteCommand(
     std::function<frc::DifferentialDriveWheelSpeeds()> wheelSpeeds,
     frc2::PIDController leftController, frc2::PIDController rightController,
     std::function<void(volt_t, volt_t)> output,
-    wpi::ArrayRef<Subsystem*> requirements)
+    wpi::span<Subsystem* const> requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
       m_controller(controller),
@@ -75,7 +75,7 @@ RamseteCommand::RamseteCommand(
     frc::DifferentialDriveKinematics kinematics,
     std::function<void(units::meters_per_second_t, units::meters_per_second_t)>
         output,
-    wpi::ArrayRef<Subsystem*> requirements)
+    wpi::span<Subsystem* const> requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
       m_controller(controller),
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/RunCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/RunCommand.cpp
index 1e073c903e..c63e5d6eb8 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/RunCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/RunCommand.cpp
@@ -13,7 +13,7 @@ RunCommand::RunCommand(std::function<void()> toRun,
 }
 
 RunCommand::RunCommand(std::function<void()> toRun,
-                       wpi::ArrayRef<Subsystem*> requirements)
+                       wpi::span<Subsystem* const> requirements)
     : m_toRun{std::move(toRun)} {
   AddRequirements(requirements);
 }
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/ScheduleCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/ScheduleCommand.cpp
index bd580118ac..ff50bc5e2d 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/ScheduleCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/ScheduleCommand.cpp
@@ -6,10 +6,14 @@
 
 using namespace frc2;
 
-ScheduleCommand::ScheduleCommand(wpi::ArrayRef<Command*> toSchedule) {
+ScheduleCommand::ScheduleCommand(wpi::span<Command* const> toSchedule) {
   SetInsert(m_toSchedule, toSchedule);
 }
 
+ScheduleCommand::ScheduleCommand(Command* toSchedule) {
+  SetInsert(m_toSchedule, {&toSchedule, 1});
+}
+
 void ScheduleCommand::Initialize() {
   for (auto command : m_toSchedule) {
     command->Schedule();
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/StartEndCommand.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/StartEndCommand.cpp
index a53ad8a179..dc40200690 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/StartEndCommand.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/StartEndCommand.cpp
@@ -15,7 +15,7 @@ StartEndCommand::StartEndCommand(std::function<void()> onInit,
 
 StartEndCommand::StartEndCommand(std::function<void()> onInit,
                                  std::function<void()> onEnd,
-                                 wpi::ArrayRef<Subsystem*> requirements)
+                                 wpi::span<Subsystem* const> requirements)
     : m_onInit{std::move(onInit)}, m_onEnd{std::move(onEnd)} {
   AddRequirements(requirements);
 }
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/button/Button.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/button/Button.cpp
index 37e818455d..955830a672 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/button/Button.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/button/Button.cpp
@@ -20,7 +20,7 @@ Button Button::WhenPressed(std::function<void()> toRun,
 }
 
 Button Button::WhenPressed(std::function<void()> toRun,
-                           wpi::ArrayRef<Subsystem*> requirements) {
+                           wpi::span<Subsystem* const> requirements) {
   WhenActive(std::move(toRun), requirements);
   return *this;
 }
@@ -37,7 +37,7 @@ Button Button::WhileHeld(std::function<void()> toRun,
 }
 
 Button Button::WhileHeld(std::function<void()> toRun,
-                         wpi::ArrayRef<Subsystem*> requirements) {
+                         wpi::span<Subsystem* const> requirements) {
   WhileActiveContinous(std::move(toRun), requirements);
   return *this;
 }
@@ -59,7 +59,7 @@ Button Button::WhenReleased(std::function<void()> toRun,
 }
 
 Button Button::WhenReleased(std::function<void()> toRun,
-                            wpi::ArrayRef<Subsystem*> requirements) {
+                            wpi::span<Subsystem* const> requirements) {
   WhenInactive(std::move(toRun), requirements);
   return *this;
 }
diff --git a/wpilibNewCommands/src/main/native/cpp/frc2/command/button/Trigger.cpp b/wpilibNewCommands/src/main/native/cpp/frc2/command/button/Trigger.cpp
index 8b5737fc04..322420202f 100644
--- a/wpilibNewCommands/src/main/native/cpp/frc2/command/button/Trigger.cpp
+++ b/wpilibNewCommands/src/main/native/cpp/frc2/command/button/Trigger.cpp
@@ -27,12 +27,12 @@ Trigger Trigger::WhenActive(Command* command, bool interruptible) {
 
 Trigger Trigger::WhenActive(std::function<void()> toRun,
                             std::initializer_list<Subsystem*> requirements) {
-  return WhenActive(std::move(toRun), wpi::makeArrayRef(requirements.begin(),
-                                                        requirements.end()));
+  return WhenActive(std::move(toRun),
+                    {requirements.begin(), requirements.end()});
 }
 
 Trigger Trigger::WhenActive(std::function<void()> toRun,
-                            wpi::ArrayRef<Subsystem*> requirements) {
+                            wpi::span<Subsystem* const> requirements) {
   return WhenActive(InstantCommand(std::move(toRun), requirements));
 }
 
@@ -55,13 +55,12 @@ Trigger Trigger::WhileActiveContinous(Command* command, bool interruptible) {
 Trigger Trigger::WhileActiveContinous(
     std::function<void()> toRun,
     std::initializer_list<Subsystem*> requirements) {
-  return WhileActiveContinous(
-      std::move(toRun),
-      wpi::makeArrayRef(requirements.begin(), requirements.end()));
+  return WhileActiveContinous(std::move(toRun),
+                              {requirements.begin(), requirements.end()});
 }
 
-Trigger Trigger::WhileActiveContinous(std::function<void()> toRun,
-                                      wpi::ArrayRef<Subsystem*> requirements) {
+Trigger Trigger::WhileActiveContinous(
+    std::function<void()> toRun, wpi::span<Subsystem* const> requirements) {
   return WhileActiveContinous(InstantCommand(std::move(toRun), requirements));
 }
 
@@ -97,12 +96,12 @@ Trigger Trigger::WhenInactive(Command* command, bool interruptible) {
 
 Trigger Trigger::WhenInactive(std::function<void()> toRun,
                               std::initializer_list<Subsystem*> requirements) {
-  return WhenInactive(std::move(toRun), wpi::makeArrayRef(requirements.begin(),
-                                                          requirements.end()));
+  return WhenInactive(std::move(toRun),
+                      {requirements.begin(), requirements.end()});
 }
 
 Trigger Trigger::WhenInactive(std::function<void()> toRun,
-                              wpi::ArrayRef<Subsystem*> requirements) {
+                              wpi::span<Subsystem* const> requirements) {
   return WhenInactive(InstantCommand(std::move(toRun), requirements));
 }
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/Command.h b/wpilibNewCommands/src/main/native/include/frc2/command/Command.h
index 7bdc1c926a..b2ff4d9a26 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/Command.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/Command.h
@@ -10,9 +10,9 @@
 #include <string>
 
 #include <units/time.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/Demangle.h>
 #include <wpi/SmallSet.h>
+#include <wpi/span.h>
 
 #include "frc2/command/Subsystem.h"
 
@@ -140,7 +140,7 @@ class Command {
    */
   SequentialCommandGroup BeforeStarting(
       std::function<void()> toRun,
-      wpi::ArrayRef<Subsystem*> requirements = {}) &&;
+      wpi::span<Subsystem* const> requirements = {}) &&;
 
   /**
    * Decorates this command with a runnable to run after the command finishes.
@@ -162,7 +162,7 @@ class Command {
    */
   SequentialCommandGroup AndThen(
       std::function<void()> toRun,
-      wpi::ArrayRef<Subsystem*> requirements = {}) &&;
+      wpi::span<Subsystem* const> requirements = {}) &&;
 
   /**
    * Decorates this command to run perpetually, ignoring its ordinary end
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/CommandBase.h b/wpilibNewCommands/src/main/native/include/frc2/command/CommandBase.h
index b37f3df417..473daae48c 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/CommandBase.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/CommandBase.h
@@ -10,8 +10,8 @@
 
 #include <frc/smartdashboard/Sendable.h>
 #include <frc/smartdashboard/SendableHelper.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallSet.h>
+#include <wpi/span.h>
 
 #include "frc2/command/Command.h"
 
@@ -35,7 +35,7 @@ class CommandBase : public Command,
    *
    * @param requirements the requirements to add
    */
-  void AddRequirements(wpi::ArrayRef<Subsystem*> requirements);
+  void AddRequirements(wpi::span<Subsystem* const> requirements);
 
   void AddRequirements(wpi::SmallSet<Subsystem*, 4> requirements);
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/CommandGroupBase.h b/wpilibNewCommands/src/main/native/include/frc2/command/CommandGroupBase.h
index aa940c6182..0ba17d7d16 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/CommandGroupBase.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/CommandGroupBase.h
@@ -8,7 +8,7 @@
 #include <memory>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 
@@ -25,10 +25,19 @@ class CommandGroupBase : public CommandBase {
    * Requires that the specified command not have been already allocated to a
    * CommandGroup. Reports an error if the command is already grouped.
    *
-   * @param commands The command to check
+   * @param command The command to check
    * @return True if all the command is ungrouped.
    */
-  static bool RequireUngrouped(Command& command);
+  static bool RequireUngrouped(const Command& command);
+
+  /**
+   * Requires that the specified command not have been already allocated to a
+   * CommandGroup. Reports an error if the command is already grouped.
+   *
+   * @param command The command to check
+   * @return True if all the command is ungrouped.
+   */
+  static bool RequireUngrouped(const Command* command);
 
   /**
    * Requires that the specified commands not have been already allocated to a
@@ -37,7 +46,7 @@ class CommandGroupBase : public CommandBase {
    * @param commands The commands to check
    * @return True if all the commands are ungrouped.
    */
-  static bool RequireUngrouped(wpi::ArrayRef<std::unique_ptr<Command>>);
+  static bool RequireUngrouped(wpi::span<const std::unique_ptr<Command>>);
 
   /**
    * Requires that the specified commands not have been already allocated to a
@@ -46,7 +55,7 @@ class CommandGroupBase : public CommandBase {
    * @param commands The commands to check
    * @return True if all the commands are ungrouped.
    */
-  static bool RequireUngrouped(std::initializer_list<Command*>);
+  static bool RequireUngrouped(std::initializer_list<const Command*>);
 
   /**
    * Adds the given commands to the command group.
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/CommandScheduler.h b/wpilibNewCommands/src/main/native/include/frc2/command/CommandScheduler.h
index 26de78319f..e041670c09 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/CommandScheduler.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/CommandScheduler.h
@@ -13,8 +13,8 @@
 #include <frc/smartdashboard/Sendable.h>
 #include <frc/smartdashboard/SendableHelper.h>
 #include <units/time.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/FunctionExtras.h>
+#include <wpi/span.h>
 
 namespace frc2 {
 class Command;
@@ -92,7 +92,7 @@ class CommandScheduler final : public frc::Sendable,
    * @param interruptible whether the commands should be interruptible
    * @param commands      the commands to schedule
    */
-  void Schedule(bool interruptible, wpi::ArrayRef<Command*> commands);
+  void Schedule(bool interruptible, wpi::span<Command* const> commands);
 
   /**
    * Schedules multiple commands for execution.  Does nothing if the command is
@@ -112,7 +112,7 @@ class CommandScheduler final : public frc::Sendable,
    *
    * @param commands the commands to schedule
    */
-  void Schedule(wpi::ArrayRef<Command*> commands);
+  void Schedule(wpi::span<Command* const> commands);
 
   /**
    * Schedules multiple commands for execution, with interruptible defaulted to
@@ -160,10 +160,10 @@ class CommandScheduler final : public frc::Sendable,
   void UnregisterSubsystem(Subsystem* subsystem);
 
   void RegisterSubsystem(std::initializer_list<Subsystem*> subsystems);
-  void RegisterSubsystem(wpi::ArrayRef<Subsystem*> subsystems);
+  void RegisterSubsystem(wpi::span<Subsystem* const> subsystems);
 
   void UnregisterSubsystem(std::initializer_list<Subsystem*> subsystems);
-  void UnregisterSubsystem(wpi::ArrayRef<Subsystem*> subsystems);
+  void UnregisterSubsystem(wpi::span<Subsystem* const> subsystems);
 
   /**
    * Sets the default command for a subsystem.  Registers that subsystem if it
@@ -223,7 +223,7 @@ class CommandScheduler final : public frc::Sendable,
    *
    * @param commands the commands to cancel
    */
-  void Cancel(wpi::ArrayRef<Command*> commands);
+  void Cancel(wpi::span<Command* const> commands);
 
   /**
    * Cancels commands. The scheduler will only call Command::End()
@@ -261,7 +261,7 @@ class CommandScheduler final : public frc::Sendable,
    * @param commands the command to query
    * @return whether the command is currently scheduled
    */
-  bool IsScheduled(wpi::ArrayRef<const Command*> commands) const;
+  bool IsScheduled(wpi::span<const Command* const> commands) const;
 
   /**
    * Whether the given commands are running.  Note that this only works on
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/FunctionalCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/FunctionalCommand.h
index f3b60d1878..31b2ada3f9 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/FunctionalCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/FunctionalCommand.h
@@ -7,7 +7,7 @@
 #include <functional>
 #include <initializer_list>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -52,7 +52,7 @@ class FunctionalCommand : public CommandHelper<CommandBase, FunctionalCommand> {
                     std::function<void()> onExecute,
                     std::function<void(bool)> onEnd,
                     std::function<bool()> isFinished,
-                    wpi::ArrayRef<Subsystem*> requirements = {});
+                    wpi::span<Subsystem* const> requirements = {});
 
   FunctionalCommand(FunctionalCommand&& other) = default;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/InstantCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/InstantCommand.h
index 08651ebbe1..3aba587e24 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/InstantCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/InstantCommand.h
@@ -7,7 +7,7 @@
 #include <functional>
 #include <initializer_list>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -38,7 +38,7 @@ class InstantCommand : public CommandHelper<CommandBase, InstantCommand> {
    * @param requirements the subsystems required by this command
    */
   explicit InstantCommand(std::function<void()> toRun,
-                          wpi::ArrayRef<Subsystem*> requirements = {});
+                          wpi::span<Subsystem* const> requirements = {});
 
   InstantCommand(InstantCommand&& other) = default;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/MecanumControllerCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/MecanumControllerCommand.h
index 9427be81ab..90d3033a32 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/MecanumControllerCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/MecanumControllerCommand.h
@@ -21,7 +21,7 @@
 #include <units/length.h>
 #include <units/velocity.h>
 #include <units/voltage.h>
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "CommandBase.h"
 #include "CommandHelper.h"
@@ -204,7 +204,7 @@ class MecanumControllerCommand
       std::function<void(units::volt_t, units::volt_t, units::volt_t,
                          units::volt_t)>
           output,
-      wpi::ArrayRef<Subsystem*> requirements = {});
+      wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Constructs a new MecanumControllerCommand that when executed will follow
@@ -257,7 +257,7 @@ class MecanumControllerCommand
       std::function<void(units::volt_t, units::volt_t, units::volt_t,
                          units::volt_t)>
           output,
-      wpi::ArrayRef<Subsystem*> requirements = {});
+      wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Constructs a new MecanumControllerCommand that when executed will follow
@@ -373,7 +373,7 @@ class MecanumControllerCommand
                          units::meters_per_second_t,
                          units::meters_per_second_t)>
           output,
-      wpi::ArrayRef<Subsystem*> requirements = {});
+      wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Constructs a new MecanumControllerCommand that when executed will follow
@@ -413,7 +413,7 @@ class MecanumControllerCommand
                          units::meters_per_second_t,
                          units::meters_per_second_t)>
           output,
-      wpi::ArrayRef<Subsystem*> requirements = {});
+      wpi::span<Subsystem* const> requirements = {});
 
   void Initialize() override;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/NotifierCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/NotifierCommand.h
index 4083273450..f4f31e3790 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/NotifierCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/NotifierCommand.h
@@ -9,7 +9,7 @@
 
 #include <frc/Notifier.h>
 #include <units/time.h>
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -45,7 +45,7 @@ class NotifierCommand : public CommandHelper<CommandBase, NotifierCommand> {
    * @param requirements the subsystems required by this command
    */
   NotifierCommand(std::function<void()> toRun, units::second_t period,
-                  wpi::ArrayRef<Subsystem*> requirements = {});
+                  wpi::span<Subsystem* const> requirements = {});
 
   NotifierCommand(NotifierCommand&& other);
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/PIDCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/PIDCommand.h
index 918d44e60c..31baf9eb43 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/PIDCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/PIDCommand.h
@@ -8,6 +8,7 @@
 #include <initializer_list>
 
 #include <frc/controller/PIDController.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -53,7 +54,7 @@ class PIDCommand : public CommandHelper<CommandBase, PIDCommand> {
              std::function<double()> measurementSource,
              std::function<double()> setpointSource,
              std::function<void(double)> useOutput,
-             wpi::ArrayRef<Subsystem*> requirements = {});
+             wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Creates a new PIDCommand, which controls the given output with a
@@ -83,7 +84,7 @@ class PIDCommand : public CommandHelper<CommandBase, PIDCommand> {
   PIDCommand(PIDController controller,
              std::function<double()> measurementSource, double setpoint,
              std::function<void(double)> useOutput,
-             wpi::ArrayRef<Subsystem*> requirements = {});
+             wpi::span<Subsystem* const> requirements = {});
 
   PIDCommand(PIDCommand&& other) = default;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/ProfiledPIDCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/ProfiledPIDCommand.h
index 747b7ca767..b02c81d249 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/ProfiledPIDCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/ProfiledPIDCommand.h
@@ -10,7 +10,7 @@
 
 #include <frc/controller/ProfiledPIDController.h>
 #include <units/time.h>
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -70,7 +70,7 @@ class ProfiledPIDCommand
                      std::function<Distance_t()> measurementSource,
                      std::function<State()> goalSource,
                      std::function<void(double, State)> useOutput,
-                     wpi::ArrayRef<Subsystem*> requirements = {})
+                     wpi::span<Subsystem* const> requirements = {})
       : m_controller{controller},
         m_measurement{std::move(measurementSource)},
         m_goal{std::move(goalSource)},
@@ -114,7 +114,7 @@ class ProfiledPIDCommand
                      std::function<Distance_t()> measurementSource,
                      std::function<Distance_t()> goalSource,
                      std::function<void(double, State)> useOutput,
-                     wpi::ArrayRef<Subsystem*> requirements = {})
+                     wpi::span<Subsystem* const> requirements = {})
       : ProfiledPIDCommand(
             controller, measurementSource,
             [&goalSource]() {
@@ -153,7 +153,7 @@ class ProfiledPIDCommand
   ProfiledPIDCommand(frc::ProfiledPIDController<Distance> controller,
                      std::function<Distance_t()> measurementSource, State goal,
                      std::function<void(double, State)> useOutput,
-                     wpi::ArrayRef<Subsystem*> requirements = {})
+                     wpi::span<Subsystem* const> requirements = {})
       : ProfiledPIDCommand(
             controller, measurementSource, [goal] { return goal; }, useOutput,
             requirements) {}
@@ -191,7 +191,7 @@ class ProfiledPIDCommand
                      std::function<Distance_t()> measurementSource,
                      Distance_t goal,
                      std::function<void(double, State)> useOutput,
-                     wpi::ArrayRef<Subsystem*> requirements = {})
+                     wpi::span<Subsystem* const> requirements = {})
       : ProfiledPIDCommand(
             controller, measurementSource, [goal] { return goal; }, useOutput,
             requirements) {}
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/ProxyScheduleCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/ProxyScheduleCommand.h
index 439d57227a..ad603f941c 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/ProxyScheduleCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/ProxyScheduleCommand.h
@@ -4,8 +4,8 @@
 
 #pragma once
 
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallVector.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -27,7 +27,9 @@ class ProxyScheduleCommand
    *
    * @param toSchedule the commands to schedule
    */
-  explicit ProxyScheduleCommand(wpi::ArrayRef<Command*> toSchedule);
+  explicit ProxyScheduleCommand(wpi::span<Command* const> toSchedule);
+
+  explicit ProxyScheduleCommand(Command* toSchedule);
 
   ProxyScheduleCommand(ProxyScheduleCommand&& other) = default;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/RamseteCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/RamseteCommand.h
index 79e418be35..5f8499729d 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/RamseteCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/RamseteCommand.h
@@ -17,7 +17,7 @@
 #include <frc/trajectory/Trajectory.h>
 #include <units/length.h>
 #include <units/voltage.h>
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -114,7 +114,7 @@ class RamseteCommand : public CommandHelper<CommandBase, RamseteCommand> {
                  frc2::PIDController leftController,
                  frc2::PIDController rightController,
                  std::function<void(units::volt_t, units::volt_t)> output,
-                 wpi::ArrayRef<Subsystem*> requirements = {});
+                 wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Constructs a new RamseteCommand that, when executed, will follow the
@@ -162,7 +162,7 @@ class RamseteCommand : public CommandHelper<CommandBase, RamseteCommand> {
                  std::function<void(units::meters_per_second_t,
                                     units::meters_per_second_t)>
                      output,
-                 wpi::ArrayRef<Subsystem*> requirements = {});
+                 wpi::span<Subsystem* const> requirements = {});
 
   void Initialize() override;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/RunCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/RunCommand.h
index 2d994705f6..510840ef34 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/RunCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/RunCommand.h
@@ -7,7 +7,7 @@
 #include <functional>
 #include <initializer_list>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -39,7 +39,7 @@ class RunCommand : public CommandHelper<CommandBase, RunCommand> {
    * @param requirements the subsystems to require
    */
   explicit RunCommand(std::function<void()> toRun,
-                      wpi::ArrayRef<Subsystem*> requirements = {});
+                      wpi::span<Subsystem* const> requirements = {});
 
   RunCommand(RunCommand&& other) = default;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/ScheduleCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/ScheduleCommand.h
index 8a426a75b6..ca476d0779 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/ScheduleCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/ScheduleCommand.h
@@ -4,8 +4,8 @@
 
 #pragma once
 
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallVector.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -26,7 +26,9 @@ class ScheduleCommand : public CommandHelper<CommandBase, ScheduleCommand> {
    *
    * @param toSchedule the commands to schedule
    */
-  explicit ScheduleCommand(wpi::ArrayRef<Command*> toSchedule);
+  explicit ScheduleCommand(wpi::span<Command* const> toSchedule);
+
+  explicit ScheduleCommand(Command* toSchedule);
 
   ScheduleCommand(ScheduleCommand&& other) = default;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/SelectCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/SelectCommand.h
index 34062a3e26..b4e7f898b3 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/SelectCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/SelectCommand.h
@@ -59,7 +59,7 @@ class SelectCommand : public CommandHelper<CommandBase, SelectCommand<Key>> {
      ...);
 
     for (auto&& command : foo) {
-      if (!CommandGroupBase::RequireUngrouped(command.second)) {
+      if (!CommandGroupBase::RequireUngrouped(*command.second)) {
         return;
       }
     }
@@ -76,7 +76,7 @@ class SelectCommand : public CommandHelper<CommandBase, SelectCommand<Key>> {
       std::vector<std::pair<Key, std::unique_ptr<Command>>>&& commands)
       : m_selector{std::move(selector)} {
     for (auto&& command : commands) {
-      if (!CommandGroupBase::RequireUngrouped(command.second)) {
+      if (!CommandGroupBase::RequireUngrouped(*command.second)) {
         return;
       }
     }
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/SequentialCommandGroup.h b/wpilibNewCommands/src/main/native/include/frc2/command/SequentialCommandGroup.h
index 253abb28c1..4b09544b12 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/SequentialCommandGroup.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/SequentialCommandGroup.h
@@ -15,8 +15,6 @@
 #include <utility>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
-
 #include "frc2/command/CommandGroupBase.h"
 #include "frc2/command/CommandHelper.h"
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/SetUtilities.h b/wpilibNewCommands/src/main/native/include/frc2/command/SetUtilities.h
index fc7efe414c..d40fbecaa6 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/SetUtilities.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/SetUtilities.h
@@ -4,12 +4,12 @@
 
 #pragma once
 
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallVector.h>
+#include <wpi/span.h>
 
 namespace frc2 {
 template <typename T>
-void SetInsert(wpi::SmallVectorImpl<T*>& vector, wpi::ArrayRef<T*> toAdd) {
+void SetInsert(wpi::SmallVectorImpl<T*>& vector, wpi::span<T* const> toAdd) {
   for (auto addCommand : toAdd) {
     bool exists = false;
     for (auto existingCommand : vector) {
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/StartEndCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/StartEndCommand.h
index 4c239d0e06..d364696360 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/StartEndCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/StartEndCommand.h
@@ -7,7 +7,7 @@
 #include <functional>
 #include <initializer_list>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -42,7 +42,7 @@ class StartEndCommand : public CommandHelper<CommandBase, StartEndCommand> {
    * @param requirements the subsystems required by this command
    */
   StartEndCommand(std::function<void()> onInit, std::function<void()> onEnd,
-                  wpi::ArrayRef<Subsystem*> requirements = {});
+                  wpi::span<Subsystem* const> requirements = {});
 
   StartEndCommand(StartEndCommand&& other) = default;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.h
index 459cec992a..13733fe6b1 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.h
@@ -19,7 +19,7 @@
 #include <units/length.h>
 #include <units/time.h>
 #include <units/voltage.h>
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "CommandBase.h"
 #include "CommandHelper.h"
@@ -167,7 +167,7 @@ class SwerveControllerCommand
       std::function<frc::Rotation2d()> desiredRotation,
       std::function<void(std::array<frc::SwerveModuleState, NumModules>)>
           output,
-      wpi::ArrayRef<Subsystem*> requirements = {});
+      wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Constructs a new SwerveControllerCommand that when executed will follow the
@@ -205,7 +205,7 @@ class SwerveControllerCommand
       frc::ProfiledPIDController<units::radians> thetaController,
       std::function<void(std::array<frc::SwerveModuleState, NumModules>)>
           output,
-      wpi::ArrayRef<Subsystem*> requirements = {});
+      wpi::span<Subsystem* const> requirements = {});
 
   void Initialize() override;
 
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.inc b/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.inc
index 19fb719365..1f65b788f1 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.inc
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/SwerveControllerCommand.inc
@@ -56,7 +56,7 @@ SwerveControllerCommand<NumModules>::SwerveControllerCommand(
     frc::ProfiledPIDController<units::radians> thetaController,
     std::function<frc::Rotation2d()> desiredRotation,
     std::function<void(std::array<frc::SwerveModuleState, NumModules>)> output,
-    wpi::ArrayRef<Subsystem*> requirements)
+    wpi::span<Subsystem* const> requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
       m_kinematics(kinematics),
@@ -73,7 +73,7 @@ SwerveControllerCommand<NumModules>::SwerveControllerCommand(
     frc2::PIDController xController, frc2::PIDController yController,
     frc::ProfiledPIDController<units::radians> thetaController,
     std::function<void(std::array<frc::SwerveModuleState, NumModules>)> output,
-    wpi::ArrayRef<Subsystem*> requirements)
+    wpi::span<Subsystem* const> requirements)
     : m_trajectory(std::move(trajectory)),
       m_pose(std::move(pose)),
       m_kinematics(kinematics),
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/TrapezoidProfileCommand.h b/wpilibNewCommands/src/main/native/include/frc2/command/TrapezoidProfileCommand.h
index d3e33dcfdb..4cfbd23177 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/TrapezoidProfileCommand.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/TrapezoidProfileCommand.h
@@ -9,7 +9,7 @@
 
 #include <frc/Timer.h>
 #include <frc/trajectory/TrapezoidProfile.h>
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/CommandBase.h"
 #include "frc2/command/CommandHelper.h"
@@ -54,7 +54,7 @@ class TrapezoidProfileCommand
    */
   TrapezoidProfileCommand(frc::TrapezoidProfile<Distance> profile,
                           std::function<void(State)> output,
-                          wpi::ArrayRef<Subsystem*> requirements = {})
+                          wpi::span<Subsystem* const> requirements = {})
       : m_profile(profile), m_output(output) {
     this->AddRequirements(requirements);
   }
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/button/Button.h b/wpilibNewCommands/src/main/native/include/frc2/command/button/Button.h
index faff8f4e7d..3540432a53 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/button/Button.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/button/Button.h
@@ -8,7 +8,7 @@
 #include <initializer_list>
 #include <utility>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "Trigger.h"
 
@@ -79,7 +79,7 @@ class Button : public Trigger {
    * @param requirements the required subsystems.
    */
   Button WhenPressed(std::function<void()> toRun,
-                     wpi::ArrayRef<Subsystem*> requirements = {});
+                     wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Binds a command to be started repeatedly while the button is pressed, and
@@ -125,7 +125,7 @@ class Button : public Trigger {
    * @param requirements the required subsystems.
    */
   Button WhileHeld(std::function<void()> toRun,
-                   wpi::ArrayRef<Subsystem*> requirements = {});
+                   wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Binds a command to be started when the button is pressed, and canceled
@@ -199,7 +199,7 @@ class Button : public Trigger {
    * @param requirements the required subsystems.
    */
   Button WhenReleased(std::function<void()> toRun,
-                      wpi::ArrayRef<Subsystem*> requirements = {});
+                      wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Binds a command to start when the button is pressed, and be canceled when
diff --git a/wpilibNewCommands/src/main/native/include/frc2/command/button/Trigger.h b/wpilibNewCommands/src/main/native/include/frc2/command/button/Trigger.h
index 101b395bc0..67a194f5de 100644
--- a/wpilibNewCommands/src/main/native/include/frc2/command/button/Trigger.h
+++ b/wpilibNewCommands/src/main/native/include/frc2/command/button/Trigger.h
@@ -9,7 +9,7 @@
 #include <memory>
 #include <utility>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc2/command/Command.h"
 #include "frc2/command/CommandScheduler.h"
@@ -101,7 +101,7 @@ class Trigger {
    * @paaram requirements the required subsystems.
    */
   Trigger WhenActive(std::function<void()> toRun,
-                     wpi::ArrayRef<Subsystem*> requirements = {});
+                     wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Binds a command to be started repeatedly while the trigger is active, and
@@ -161,7 +161,7 @@ class Trigger {
    * @param requirements the required subsystems.
    */
   Trigger WhileActiveContinous(std::function<void()> toRun,
-                               wpi::ArrayRef<Subsystem*> requirements = {});
+                               wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Binds a command to be started when the trigger becomes active, and
@@ -261,7 +261,7 @@ class Trigger {
    * @param requirements the required subsystems.
    */
   Trigger WhenInactive(std::function<void()> toRun,
-                       wpi::ArrayRef<Subsystem*> requirements = {});
+                       wpi::span<Subsystem* const> requirements = {});
 
   /**
    * Binds a command to start when the trigger becomes active, and be canceled
diff --git a/wpilibOldCommands/src/main/native/cpp/commands/Scheduler.cpp b/wpilibOldCommands/src/main/native/cpp/commands/Scheduler.cpp
index 4543dc0cf2..8baa62f5c3 100644
--- a/wpilibOldCommands/src/main/native/cpp/commands/Scheduler.cpp
+++ b/wpilibOldCommands/src/main/native/cpp/commands/Scheduler.cpp
@@ -165,7 +165,7 @@ void Scheduler::InitSendable(SendableBuilder& builder) {
   builder.SetUpdateTable([=]() {
     // Get the list of possible commands to cancel
     auto new_toCancel = cancelEntry.GetValue();
-    wpi::ArrayRef<double> toCancel;
+    wpi::span<const double> toCancel;
     if (new_toCancel) {
       toCancel = new_toCancel->GetDoubleArray();
     }
diff --git a/wpilibc/src/main/native/cpp/AddressableLED.cpp b/wpilibc/src/main/native/cpp/AddressableLED.cpp
index 320eac2463..759c3864d5 100644
--- a/wpilibc/src/main/native/cpp/AddressableLED.cpp
+++ b/wpilibc/src/main/native/cpp/AddressableLED.cpp
@@ -51,7 +51,7 @@ void AddressableLED::SetLength(int length) {
 static_assert(sizeof(AddressableLED::LEDData) == sizeof(HAL_AddressableLEDData),
               "LED Structs MUST be the same size");
 
-void AddressableLED::SetData(wpi::ArrayRef<LEDData> ledData) {
+void AddressableLED::SetData(wpi::span<const LEDData> ledData) {
   int32_t status = 0;
   HAL_WriteAddressableLEDData(m_handle, ledData.begin(), ledData.size(),
                               &status);
diff --git a/wpilibc/src/main/native/cpp/SPI.cpp b/wpilibc/src/main/native/cpp/SPI.cpp
index 91df304d54..74df512daf 100644
--- a/wpilibc/src/main/native/cpp/SPI.cpp
+++ b/wpilibc/src/main/native/cpp/SPI.cpp
@@ -260,7 +260,8 @@ void SPI::FreeAuto() {
   FRC_CheckErrorStatus(status, "Port {}", m_port);
 }
 
-void SPI::SetAutoTransmitData(wpi::ArrayRef<uint8_t> dataToSend, int zeroSize) {
+void SPI::SetAutoTransmitData(wpi::span<const uint8_t> dataToSend,
+                              int zeroSize) {
   int32_t status = 0;
   HAL_SetSPIAutoTransmitData(m_port, dataToSend.data(), dataToSend.size(),
                              zeroSize, &status);
diff --git a/wpilibc/src/main/native/cpp/drive/RobotDriveBase.cpp b/wpilibc/src/main/native/cpp/drive/RobotDriveBase.cpp
index 005eb08b7d..5dcd2876c1 100644
--- a/wpilibc/src/main/native/cpp/drive/RobotDriveBase.cpp
+++ b/wpilibc/src/main/native/cpp/drive/RobotDriveBase.cpp
@@ -42,7 +42,7 @@ double RobotDriveBase::ApplyDeadband(double value, double deadband) {
   }
 }
 
-void RobotDriveBase::Normalize(wpi::MutableArrayRef<double> wheelSpeeds) {
+void RobotDriveBase::Normalize(wpi::span<double> wheelSpeeds) {
   double maxMagnitude = std::abs(wheelSpeeds[0]);
   for (size_t i = 1; i < wheelSpeeds.size(); i++) {
     double temp = std::abs(wheelSpeeds[i]);
diff --git a/wpilibc/src/main/native/cpp/shuffleboard/ShuffleboardContainer.cpp b/wpilibc/src/main/native/cpp/shuffleboard/ShuffleboardContainer.cpp
index bf36ea66fb..2112a4d317 100644
--- a/wpilibc/src/main/native/cpp/shuffleboard/ShuffleboardContainer.cpp
+++ b/wpilibc/src/main/native/cpp/shuffleboard/ShuffleboardContainer.cpp
@@ -110,17 +110,17 @@ SimpleWidget& ShuffleboardContainer::Add(std::string_view title,
 }
 
 SimpleWidget& ShuffleboardContainer::Add(std::string_view title,
-                                         wpi::ArrayRef<bool> defaultValue) {
+                                         wpi::span<const bool> defaultValue) {
   return Add(title, nt::Value::MakeBooleanArray(defaultValue));
 }
 
 SimpleWidget& ShuffleboardContainer::Add(std::string_view title,
-                                         wpi::ArrayRef<double> defaultValue) {
+                                         wpi::span<const double> defaultValue) {
   return Add(title, nt::Value::MakeDoubleArray(defaultValue));
 }
 
 SimpleWidget& ShuffleboardContainer::Add(
-    std::string_view title, wpi::ArrayRef<std::string> defaultValue) {
+    std::string_view title, wpi::span<const std::string> defaultValue) {
   return Add(title, nt::Value::MakeStringArray(defaultValue));
 }
 
@@ -254,17 +254,17 @@ SimpleWidget& ShuffleboardContainer::AddPersistent(
 }
 
 SimpleWidget& ShuffleboardContainer::AddPersistent(
-    std::string_view title, wpi::ArrayRef<bool> defaultValue) {
+    std::string_view title, wpi::span<const bool> defaultValue) {
   return AddPersistent(title, nt::Value::MakeBooleanArray(defaultValue));
 }
 
 SimpleWidget& ShuffleboardContainer::AddPersistent(
-    std::string_view title, wpi::ArrayRef<double> defaultValue) {
+    std::string_view title, wpi::span<const double> defaultValue) {
   return AddPersistent(title, nt::Value::MakeDoubleArray(defaultValue));
 }
 
 SimpleWidget& ShuffleboardContainer::AddPersistent(
-    std::string_view title, wpi::ArrayRef<std::string> defaultValue) {
+    std::string_view title, wpi::span<const std::string> defaultValue) {
   return AddPersistent(title, nt::Value::MakeStringArray(defaultValue));
 }
 
diff --git a/wpilibc/src/main/native/cpp/smartdashboard/FieldObject2d.cpp b/wpilibc/src/main/native/cpp/smartdashboard/FieldObject2d.cpp
index 1483716da6..bad7288aee 100644
--- a/wpilibc/src/main/native/cpp/smartdashboard/FieldObject2d.cpp
+++ b/wpilibc/src/main/native/cpp/smartdashboard/FieldObject2d.cpp
@@ -28,12 +28,12 @@ FieldObject2d& FieldObject2d::operator=(FieldObject2d&& rhs) {
 }
 
 void FieldObject2d::SetPose(const Pose2d& pose) {
-  SetPoses(wpi::makeArrayRef(pose));
+  SetPoses({pose});
 }
 
 void FieldObject2d::SetPose(units::meter_t x, units::meter_t y,
                             Rotation2d rotation) {
-  SetPoses(wpi::makeArrayRef(Pose2d{x, y, rotation}));
+  SetPoses({{x, y, rotation}});
 }
 
 Pose2d FieldObject2d::GetPose() const {
@@ -45,14 +45,14 @@ Pose2d FieldObject2d::GetPose() const {
   return m_poses[0];
 }
 
-void FieldObject2d::SetPoses(wpi::ArrayRef<Pose2d> poses) {
+void FieldObject2d::SetPoses(wpi::span<const Pose2d> poses) {
   std::scoped_lock lock(m_mutex);
   m_poses.assign(poses.begin(), poses.end());
   UpdateEntry();
 }
 
 void FieldObject2d::SetPoses(std::initializer_list<Pose2d> poses) {
-  SetPoses(wpi::makeArrayRef(poses.begin(), poses.end()));
+  SetPoses({poses.begin(), poses.end()});
 }
 
 void FieldObject2d::SetTrajectory(const Trajectory& trajectory) {
@@ -71,7 +71,7 @@ std::vector<Pose2d> FieldObject2d::GetPoses() const {
   return std::vector<Pose2d>(m_poses.begin(), m_poses.end());
 }
 
-wpi::ArrayRef<Pose2d> FieldObject2d::GetPoses(
+wpi::span<const Pose2d> FieldObject2d::GetPoses(
     wpi::SmallVectorImpl<Pose2d>& out) const {
   std::scoped_lock lock(m_mutex);
   UpdateFromEntry();
diff --git a/wpilibc/src/main/native/cpp/smartdashboard/SendableBuilderImpl.cpp b/wpilibc/src/main/native/cpp/smartdashboard/SendableBuilderImpl.cpp
index 7a3a5f009f..3e294dc337 100644
--- a/wpilibc/src/main/native/cpp/smartdashboard/SendableBuilderImpl.cpp
+++ b/wpilibc/src/main/native/cpp/smartdashboard/SendableBuilderImpl.cpp
@@ -177,7 +177,7 @@ void SendableBuilderImpl::AddStringProperty(
 
 void SendableBuilderImpl::AddBooleanArrayProperty(
     std::string_view key, std::function<std::vector<int>()> getter,
-    std::function<void(wpi::ArrayRef<int>)> setter) {
+    std::function<void(wpi::span<const int>)> setter) {
   m_properties.emplace_back(*m_table, key);
   if (getter) {
     m_properties.back().update = [=](nt::NetworkTableEntry entry,
@@ -203,7 +203,7 @@ void SendableBuilderImpl::AddBooleanArrayProperty(
 
 void SendableBuilderImpl::AddDoubleArrayProperty(
     std::string_view key, std::function<std::vector<double>()> getter,
-    std::function<void(wpi::ArrayRef<double>)> setter) {
+    std::function<void(wpi::span<const double>)> setter) {
   m_properties.emplace_back(*m_table, key);
   if (getter) {
     m_properties.back().update = [=](nt::NetworkTableEntry entry,
@@ -229,7 +229,7 @@ void SendableBuilderImpl::AddDoubleArrayProperty(
 
 void SendableBuilderImpl::AddStringArrayProperty(
     std::string_view key, std::function<std::vector<std::string>()> getter,
-    std::function<void(wpi::ArrayRef<std::string>)> setter) {
+    std::function<void(wpi::span<const std::string>)> setter) {
   m_properties.emplace_back(*m_table, key);
   if (getter) {
     m_properties.back().update = [=](nt::NetworkTableEntry entry,
@@ -331,8 +331,8 @@ void SendableBuilderImpl::AddSmallStringProperty(
 
 void SendableBuilderImpl::AddSmallBooleanArrayProperty(
     std::string_view key,
-    std::function<wpi::ArrayRef<int>(wpi::SmallVectorImpl<int>& buf)> getter,
-    std::function<void(wpi::ArrayRef<int>)> setter) {
+    std::function<wpi::span<const int>(wpi::SmallVectorImpl<int>& buf)> getter,
+    std::function<void(wpi::span<const int>)> setter) {
   m_properties.emplace_back(*m_table, key);
   if (getter) {
     m_properties.back().update = [=](nt::NetworkTableEntry entry,
@@ -359,9 +359,9 @@ void SendableBuilderImpl::AddSmallBooleanArrayProperty(
 
 void SendableBuilderImpl::AddSmallDoubleArrayProperty(
     std::string_view key,
-    std::function<wpi::ArrayRef<double>(wpi::SmallVectorImpl<double>& buf)>
+    std::function<wpi::span<const double>(wpi::SmallVectorImpl<double>& buf)>
         getter,
-    std::function<void(wpi::ArrayRef<double>)> setter) {
+    std::function<void(wpi::span<const double>)> setter) {
   m_properties.emplace_back(*m_table, key);
   if (getter) {
     m_properties.back().update = [=](nt::NetworkTableEntry entry,
@@ -389,9 +389,9 @@ void SendableBuilderImpl::AddSmallDoubleArrayProperty(
 void SendableBuilderImpl::AddSmallStringArrayProperty(
     std::string_view key,
     std::function<
-        wpi::ArrayRef<std::string>(wpi::SmallVectorImpl<std::string>& buf)>
+        wpi::span<const std::string>(wpi::SmallVectorImpl<std::string>& buf)>
         getter,
-    std::function<void(wpi::ArrayRef<std::string>)> setter) {
+    std::function<void(wpi::span<const std::string>)> setter) {
   m_properties.emplace_back(*m_table, key);
   if (getter) {
     m_properties.back().update = [=](nt::NetworkTableEntry entry,
diff --git a/wpilibc/src/main/native/cpp/smartdashboard/SmartDashboard.cpp b/wpilibc/src/main/native/cpp/smartdashboard/SmartDashboard.cpp
index d7794707f2..d8743fcb63 100644
--- a/wpilibc/src/main/native/cpp/smartdashboard/SmartDashboard.cpp
+++ b/wpilibc/src/main/native/cpp/smartdashboard/SmartDashboard.cpp
@@ -170,52 +170,52 @@ std::string SmartDashboard::GetString(std::string_view keyName,
 }
 
 bool SmartDashboard::PutBooleanArray(std::string_view key,
-                                     wpi::ArrayRef<int> value) {
+                                     wpi::span<const int> value) {
   return Singleton::GetInstance().table->GetEntry(key).SetBooleanArray(value);
 }
 
 bool SmartDashboard::SetDefaultBooleanArray(std::string_view key,
-                                            wpi::ArrayRef<int> defaultValue) {
+                                            wpi::span<const int> defaultValue) {
   return Singleton::GetInstance().table->GetEntry(key).SetDefaultBooleanArray(
       defaultValue);
 }
 
 std::vector<int> SmartDashboard::GetBooleanArray(
-    std::string_view key, wpi::ArrayRef<int> defaultValue) {
+    std::string_view key, wpi::span<const int> defaultValue) {
   return Singleton::GetInstance().table->GetEntry(key).GetBooleanArray(
       defaultValue);
 }
 
 bool SmartDashboard::PutNumberArray(std::string_view key,
-                                    wpi::ArrayRef<double> value) {
+                                    wpi::span<const double> value) {
   return Singleton::GetInstance().table->GetEntry(key).SetDoubleArray(value);
 }
 
-bool SmartDashboard::SetDefaultNumberArray(std::string_view key,
-                                           wpi::ArrayRef<double> defaultValue) {
+bool SmartDashboard::SetDefaultNumberArray(
+    std::string_view key, wpi::span<const double> defaultValue) {
   return Singleton::GetInstance().table->GetEntry(key).SetDefaultDoubleArray(
       defaultValue);
 }
 
 std::vector<double> SmartDashboard::GetNumberArray(
-    std::string_view key, wpi::ArrayRef<double> defaultValue) {
+    std::string_view key, wpi::span<const double> defaultValue) {
   return Singleton::GetInstance().table->GetEntry(key).GetDoubleArray(
       defaultValue);
 }
 
 bool SmartDashboard::PutStringArray(std::string_view key,
-                                    wpi::ArrayRef<std::string> value) {
+                                    wpi::span<const std::string> value) {
   return Singleton::GetInstance().table->GetEntry(key).SetStringArray(value);
 }
 
 bool SmartDashboard::SetDefaultStringArray(
-    std::string_view key, wpi::ArrayRef<std::string> defaultValue) {
+    std::string_view key, wpi::span<const std::string> defaultValue) {
   return Singleton::GetInstance().table->GetEntry(key).SetDefaultStringArray(
       defaultValue);
 }
 
 std::vector<std::string> SmartDashboard::GetStringArray(
-    std::string_view key, wpi::ArrayRef<std::string> defaultValue) {
+    std::string_view key, wpi::span<const std::string> defaultValue) {
   return Singleton::GetInstance().table->GetEntry(key).GetStringArray(
       defaultValue);
 }
diff --git a/wpilibc/src/main/native/include/frc/AddressableLED.h b/wpilibc/src/main/native/include/frc/AddressableLED.h
index 710cf1522d..e38b4cd097 100644
--- a/wpilibc/src/main/native/include/frc/AddressableLED.h
+++ b/wpilibc/src/main/native/include/frc/AddressableLED.h
@@ -9,7 +9,7 @@
 #include <hal/AddressableLEDTypes.h>
 #include <hal/Types.h>
 #include <units/time.h>
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "util/Color.h"
 #include "util/Color8Bit.h"
@@ -107,7 +107,7 @@ class AddressableLED {
    *
    * @param ledData the buffer to write
    */
-  void SetData(wpi::ArrayRef<LEDData> ledData);
+  void SetData(wpi::span<const LEDData> ledData);
 
   /**
    * Sets the led output data.
diff --git a/wpilibc/src/main/native/include/frc/SPI.h b/wpilibc/src/main/native/include/frc/SPI.h
index 0a864be251..0f3c85737f 100644
--- a/wpilibc/src/main/native/include/frc/SPI.h
+++ b/wpilibc/src/main/native/include/frc/SPI.h
@@ -10,8 +10,8 @@
 
 #include <hal/SPITypes.h>
 #include <units/time.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/deprecated.h>
+#include <wpi/span.h>
 
 namespace frc {
 
@@ -173,7 +173,7 @@ class SPI {
    * @param dataToSend data to send (maximum 16 bytes)
    * @param zeroSize number of zeros to send after the data
    */
-  void SetAutoTransmitData(wpi::ArrayRef<uint8_t> dataToSend, int zeroSize);
+  void SetAutoTransmitData(wpi::span<const uint8_t> dataToSend, int zeroSize);
 
   /**
    * Start running the automatic SPI transfer engine at a periodic rate.
diff --git a/wpilibc/src/main/native/include/frc/drive/RobotDriveBase.h b/wpilibc/src/main/native/include/frc/drive/RobotDriveBase.h
index dea3cd33be..87003d5bf1 100644
--- a/wpilibc/src/main/native/include/frc/drive/RobotDriveBase.h
+++ b/wpilibc/src/main/native/include/frc/drive/RobotDriveBase.h
@@ -7,7 +7,7 @@
 #include <memory>
 #include <string>
 
-#include <wpi/ArrayRef.h>
+#include <wpi/span.h>
 
 #include "frc/MotorSafety.h"
 
@@ -82,7 +82,7 @@ class RobotDriveBase : public MotorSafety {
    * Normalize all wheel speeds if the magnitude of any wheel is greater than
    * 1.0.
    */
-  static void Normalize(wpi::MutableArrayRef<double> wheelSpeeds);
+  static void Normalize(wpi::span<double> wheelSpeeds);
 
   double m_deadband = 0.02;
   double m_maxOutput = 1.0;
diff --git a/wpilibc/src/main/native/include/frc/shuffleboard/ShuffleboardContainer.h b/wpilibc/src/main/native/include/frc/shuffleboard/ShuffleboardContainer.h
index e0f7b467b2..2bfc9902a0 100644
--- a/wpilibc/src/main/native/include/frc/shuffleboard/ShuffleboardContainer.h
+++ b/wpilibc/src/main/native/include/frc/shuffleboard/ShuffleboardContainer.h
@@ -12,9 +12,9 @@
 
 #include <networktables/NetworkTableEntry.h>
 #include <networktables/NetworkTableValue.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallSet.h>
 #include <wpi/StringMap.h>
+#include <wpi/span.h>
 
 #include "frc/shuffleboard/BuiltInLayouts.h"
 #include "frc/shuffleboard/LayoutType.h"
@@ -228,19 +228,7 @@ class ShuffleboardContainer : public virtual ShuffleboardValue {
    *         container with the given title
    * @see #addPersistent(String, Object) add(String title, Object defaultValue)
    */
-  SimpleWidget& Add(std::string_view title, wpi::ArrayRef<bool> defaultValue);
-
-  /**
-   * Adds a widget to this container to display the given data.
-   *
-   * @param title the title of the widget
-   * @param defaultValue  the default value of the widget
-   * @return a widget to display the sendable data
-   * @throws IllegalArgumentException if a widget already exists in this
-   *         container with the given title
-   * @see #addPersistent(String, Object) add(String title, Object defaultValue)
-   */
-  SimpleWidget& Add(std::string_view title, wpi::ArrayRef<double> defaultValue);
+  SimpleWidget& Add(std::string_view title, wpi::span<const bool> defaultValue);
 
   /**
    * Adds a widget to this container to display the given data.
@@ -253,7 +241,20 @@ class ShuffleboardContainer : public virtual ShuffleboardValue {
    * @see #addPersistent(String, Object) add(String title, Object defaultValue)
    */
   SimpleWidget& Add(std::string_view title,
-                    wpi::ArrayRef<std::string> defaultValue);
+                    wpi::span<const double> defaultValue);
+
+  /**
+   * Adds a widget to this container to display the given data.
+   *
+   * @param title the title of the widget
+   * @param defaultValue  the default value of the widget
+   * @return a widget to display the sendable data
+   * @throws IllegalArgumentException if a widget already exists in this
+   *         container with the given title
+   * @see #addPersistent(String, Object) add(String title, Object defaultValue)
+   */
+  SimpleWidget& Add(std::string_view title,
+                    wpi::span<const std::string> defaultValue);
 
   /**
    * Adds a widget to this container. The widget will display the data provided
@@ -432,7 +433,7 @@ class ShuffleboardContainer : public virtual ShuffleboardValue {
    * @see #add(String, Object) add(String title, Object defaultValue)
    */
   SimpleWidget& AddPersistent(std::string_view title,
-                              wpi::ArrayRef<bool> defaultValue);
+                              wpi::span<const bool> defaultValue);
 
   /**
    * Adds a widget to this container to display a simple piece of data.
@@ -447,7 +448,7 @@ class ShuffleboardContainer : public virtual ShuffleboardValue {
    * @see #add(String, Object) add(String title, Object defaultValue)
    */
   SimpleWidget& AddPersistent(std::string_view title,
-                              wpi::ArrayRef<double> defaultValue);
+                              wpi::span<const double> defaultValue);
 
   /**
    * Adds a widget to this container to display a simple piece of data.
@@ -462,7 +463,7 @@ class ShuffleboardContainer : public virtual ShuffleboardValue {
    * @see #add(String, Object) add(String title, Object defaultValue)
    */
   SimpleWidget& AddPersistent(std::string_view title,
-                              wpi::ArrayRef<std::string> defaultValue);
+                              wpi::span<const std::string> defaultValue);
 
   void EnableIfActuator() override;
 
diff --git a/wpilibc/src/main/native/include/frc/smartdashboard/FieldObject2d.h b/wpilibc/src/main/native/include/frc/smartdashboard/FieldObject2d.h
index 69cce223d2..29cec86d7c 100644
--- a/wpilibc/src/main/native/include/frc/smartdashboard/FieldObject2d.h
+++ b/wpilibc/src/main/native/include/frc/smartdashboard/FieldObject2d.h
@@ -12,9 +12,9 @@
 
 #include <networktables/NetworkTableEntry.h>
 #include <units/length.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallVector.h>
 #include <wpi/mutex.h>
+#include <wpi/span.h>
 
 #include "frc/geometry/Pose2d.h"
 #include "frc/geometry/Rotation2d.h"
@@ -66,7 +66,7 @@ class FieldObject2d {
    *
    * @param poses array of 2D poses
    */
-  void SetPoses(wpi::ArrayRef<Pose2d> poses);
+  void SetPoses(wpi::span<const Pose2d> poses);
 
   /**
    * Set multiple poses from an array of Pose objects.
@@ -97,9 +97,9 @@ class FieldObject2d {
    *
    * @param obj Object entry
    * @param out output SmallVector to hold 2D poses
-   * @return ArrayRef referring to output SmallVector
+   * @return span referring to output SmallVector
    */
-  wpi::ArrayRef<Pose2d> GetPoses(wpi::SmallVectorImpl<Pose2d>& out) const;
+  wpi::span<const Pose2d> GetPoses(wpi::SmallVectorImpl<Pose2d>& out) const;
 
  private:
   void UpdateEntry(bool setDefault = false);
diff --git a/wpilibc/src/main/native/include/frc/smartdashboard/SendableBuilder.h b/wpilibc/src/main/native/include/frc/smartdashboard/SendableBuilder.h
index 3ec3831cef..e7bc2d09ab 100644
--- a/wpilibc/src/main/native/include/frc/smartdashboard/SendableBuilder.h
+++ b/wpilibc/src/main/native/include/frc/smartdashboard/SendableBuilder.h
@@ -13,8 +13,8 @@
 #include <networktables/NetworkTable.h>
 #include <networktables/NetworkTableEntry.h>
 #include <networktables/NetworkTableValue.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallVector.h>
+#include <wpi/span.h>
 
 namespace frc {
 
@@ -107,7 +107,7 @@ class SendableBuilder {
    */
   virtual void AddBooleanArrayProperty(
       std::string_view key, std::function<std::vector<int>()> getter,
-      std::function<void(wpi::ArrayRef<int>)> setter) = 0;
+      std::function<void(wpi::span<const int>)> setter) = 0;
 
   /**
    * Add a double array property.
@@ -118,7 +118,7 @@ class SendableBuilder {
    */
   virtual void AddDoubleArrayProperty(
       std::string_view key, std::function<std::vector<double>()> getter,
-      std::function<void(wpi::ArrayRef<double>)> setter) = 0;
+      std::function<void(wpi::span<const double>)> setter) = 0;
 
   /**
    * Add a string array property.
@@ -129,7 +129,7 @@ class SendableBuilder {
    */
   virtual void AddStringArrayProperty(
       std::string_view key, std::function<std::vector<std::string>()> getter,
-      std::function<void(wpi::ArrayRef<std::string>)> setter) = 0;
+      std::function<void(wpi::span<const std::string>)> setter) = 0;
 
   /**
    * Add a raw property.
@@ -174,8 +174,9 @@ class SendableBuilder {
    */
   virtual void AddSmallBooleanArrayProperty(
       std::string_view key,
-      std::function<wpi::ArrayRef<int>(wpi::SmallVectorImpl<int>& buf)> getter,
-      std::function<void(wpi::ArrayRef<int>)> setter) = 0;
+      std::function<wpi::span<const int>(wpi::SmallVectorImpl<int>& buf)>
+          getter,
+      std::function<void(wpi::span<const int>)> setter) = 0;
 
   /**
    * Add a double array property (SmallVector form).
@@ -186,9 +187,9 @@ class SendableBuilder {
    */
   virtual void AddSmallDoubleArrayProperty(
       std::string_view key,
-      std::function<wpi::ArrayRef<double>(wpi::SmallVectorImpl<double>& buf)>
+      std::function<wpi::span<const double>(wpi::SmallVectorImpl<double>& buf)>
           getter,
-      std::function<void(wpi::ArrayRef<double>)> setter) = 0;
+      std::function<void(wpi::span<const double>)> setter) = 0;
 
   /**
    * Add a string array property (SmallVector form).
@@ -200,9 +201,9 @@ class SendableBuilder {
   virtual void AddSmallStringArrayProperty(
       std::string_view key,
       std::function<
-          wpi::ArrayRef<std::string>(wpi::SmallVectorImpl<std::string>& buf)>
+          wpi::span<const std::string>(wpi::SmallVectorImpl<std::string>& buf)>
           getter,
-      std::function<void(wpi::ArrayRef<std::string>)> setter) = 0;
+      std::function<void(wpi::span<const std::string>)> setter) = 0;
 
   /**
    * Add a raw property (SmallVector form).
diff --git a/wpilibc/src/main/native/include/frc/smartdashboard/SendableBuilderImpl.h b/wpilibc/src/main/native/include/frc/smartdashboard/SendableBuilderImpl.h
index 34b9d59673..10125fbd40 100644
--- a/wpilibc/src/main/native/include/frc/smartdashboard/SendableBuilderImpl.h
+++ b/wpilibc/src/main/native/include/frc/smartdashboard/SendableBuilderImpl.h
@@ -14,8 +14,8 @@
 #include <networktables/NetworkTable.h>
 #include <networktables/NetworkTableEntry.h>
 #include <networktables/NetworkTableValue.h>
-#include <wpi/ArrayRef.h>
 #include <wpi/SmallVector.h>
+#include <wpi/span.h>
 
 #include "frc/smartdashboard/SendableBuilder.h"
 
@@ -104,15 +104,15 @@ class SendableBuilderImpl : public SendableBuilder {
 
   void AddBooleanArrayProperty(
       std::string_view key, std::function<std::vector<int>()> getter,
-      std::function<void(wpi::ArrayRef<int>)> setter) override;
+      std::function<void(wpi::span<const int>)> setter) override;
 
   void AddDoubleArrayProperty(
       std::string_view key, std::function<std::vector<double>()> getter,
-      std::function<void(wpi::ArrayRef<double>)> setter) override;
+      std::function<void(wpi::span<const double>)> setter) override;
 
   void AddStringArrayProperty(
       std::string_view key, std::function<std::vector<std::string>()> getter,
-      std::function<void(wpi::ArrayRef<std::string>)> setter) override;
+      std::function<void(wpi::span<const std::string>)> setter) override;
 
   void AddRawProperty(std::string_view key, std::function<std::string()> getter,
                       std::function<void(std::string_view)> setter) override;
@@ -128,21 +128,22 @@ class SendableBuilderImpl : public SendableBuilder {
 
   void AddSmallBooleanArrayProperty(
       std::string_view key,
-      std::function<wpi::ArrayRef<int>(wpi::SmallVectorImpl<int>& buf)> getter,
-      std::function<void(wpi::ArrayRef<int>)> setter) override;
+      std::function<wpi::span<const int>(wpi::SmallVectorImpl<int>& buf)>
+          getter,
+      std::function<void(wpi::span<const int>)> setter) override;
 
   void AddSmallDoubleArrayProperty(
       std::string_view key,
-      std::function<wpi::ArrayRef<double>(wpi::SmallVectorImpl<double>& buf)>
+      std::function<wpi::span<const double>(wpi::SmallVectorImpl<double>& buf)>
           getter,
-      std::function<void(wpi::ArrayRef<double>)> setter) override;
+      std::function<void(wpi::span<const double>)> setter) override;
 
   void AddSmallStringArrayProperty(
       std::string_view key,
       std::function<
-          wpi::ArrayRef<std::string>(wpi::SmallVectorImpl<std::string>& buf)>
+          wpi::span<const std::string>(wpi::SmallVectorImpl<std::string>& buf)>
           getter,
-      std::function<void(wpi::ArrayRef<std::string>)> setter) override;
+      std::function<void(wpi::span<const std::string>)> setter) override;
 
   void AddSmallRawProperty(
       std::string_view key,
diff --git a/wpilibc/src/main/native/include/frc/smartdashboard/SmartDashboard.h b/wpilibc/src/main/native/include/frc/smartdashboard/SmartDashboard.h
index 1ce7762392..c15b26a783 100644
--- a/wpilibc/src/main/native/include/frc/smartdashboard/SmartDashboard.h
+++ b/wpilibc/src/main/native/include/frc/smartdashboard/SmartDashboard.h
@@ -11,6 +11,7 @@
 
 #include <networktables/NetworkTableEntry.h>
 #include <networktables/NetworkTableValue.h>
+#include <wpi/span.h>
 
 #include "frc/smartdashboard/ListenerExecutor.h"
 #include "frc/smartdashboard/Sendable.h"
@@ -243,7 +244,7 @@ class SmartDashboard : public Sendable, public SendableHelper<SmartDashboard> {
    *       std::vector<bool> is special-cased in C++. 0 is false, any
    *       non-zero value is true.
    */
-  static bool PutBooleanArray(std::string_view key, wpi::ArrayRef<int> value);
+  static bool PutBooleanArray(std::string_view key, wpi::span<const int> value);
 
   /**
    * Gets the current value in the table, setting it if it does not exist.
@@ -253,7 +254,7 @@ class SmartDashboard : public Sendable, public SendableHelper<SmartDashboard> {
    * @returns False if the table key exists with a different type
    */
   static bool SetDefaultBooleanArray(std::string_view key,
-                                     wpi::ArrayRef<int> defaultValue);
+                                     wpi::span<const int> defaultValue);
 
   /**
    * Returns the boolean array the key maps to.
@@ -274,7 +275,7 @@ class SmartDashboard : public Sendable, public SendableHelper<SmartDashboard> {
    *       non-zero value is true.
    */
   static std::vector<int> GetBooleanArray(std::string_view key,
-                                          wpi::ArrayRef<int> defaultValue);
+                                          wpi::span<const int> defaultValue);
 
   /**
    * Put a number array in the table.
@@ -283,7 +284,8 @@ class SmartDashboard : public Sendable, public SendableHelper<SmartDashboard> {
    * @param value The value that will be assigned.
    * @return False if the table key already exists with a different type
    */
-  static bool PutNumberArray(std::string_view key, wpi::ArrayRef<double> value);
+  static bool PutNumberArray(std::string_view key,
+                             wpi::span<const double> value);
 
   /**
    * Gets the current value in the table, setting it if it does not exist.
@@ -293,7 +295,7 @@ class SmartDashboard : public Sendable, public SendableHelper<SmartDashboard> {
    * @returns False if the table key exists with a different type
    */
   static bool SetDefaultNumberArray(std::string_view key,
-                                    wpi::ArrayRef<double> defaultValue);
+                                    wpi::span<const double> defaultValue);
 
   /**
    * Returns the number array the key maps to.
@@ -309,8 +311,8 @@ class SmartDashboard : public Sendable, public SendableHelper<SmartDashboard> {
    * @note This makes a copy of the array. If the overhead of this is a concern,
    *       use GetValue() instead.
    */
-  static std::vector<double> GetNumberArray(std::string_view key,
-                                            wpi::ArrayRef<double> defaultValue);
+  static std::vector<double> GetNumberArray(
+      std::string_view key, wpi::span<const double> defaultValue);
 
   /**
    * Put a string array in the table.
@@ -320,7 +322,7 @@ class SmartDashboard : public Sendable, public SendableHelper<SmartDashboard> {
    * @return False if the table key already exists with a different type
    */
   static bool PutStringArray(std::string_view key,
-                             wpi::ArrayRef<std::string> value);
+                             wpi::span<const std::string> value);
 
   /**
    * Gets the current value in the table, setting it if it does not exist.
@@ -330,7 +332,7 @@ class SmartDashboard : public Sendable, public SendableHelper<SmartDashboard> {
    * @returns False if the table key exists with a different type
    */
   static bool SetDefaultStringArray(std::string_view key,
-                                    wpi::ArrayRef<std::string> defaultValue);
+                                    wpi::span<const std::string> defaultValue);
 
   /**
    * Returns the string array the key maps to.
@@ -347,7 +349,7 @@ class SmartDashboard : public Sendable, public SendableHelper<SmartDashboard> {
    *       use GetValue() instead.
    */
   static std::vector<std::string> GetStringArray(
-      std::string_view key, wpi::ArrayRef<std::string> defaultValue);
+      std::string_view key, wpi::span<const std::string> defaultValue);
 
   /**
    * Put a raw value (byte array) in the table.
diff --git a/wpimath/src/main/native/cpp/jni/WPIMathJNI.cpp b/wpimath/src/main/native/cpp/jni/WPIMathJNI.cpp
index 52e68679e5..9a2083d5a0 100644
--- a/wpimath/src/main/native/cpp/jni/WPIMathJNI.cpp
+++ b/wpimath/src/main/native/cpp/jni/WPIMathJNI.cpp
@@ -62,7 +62,7 @@ std::vector<double> GetElementsFromTrajectory(
   return elements;
 }
 
-frc::Trajectory CreateTrajectoryFromElements(wpi::ArrayRef<double> elements) {
+frc::Trajectory CreateTrajectoryFromElements(wpi::span<const double> elements) {
   // Make sure that the elements have the correct length.
   assert(elements.size() % 7 == 0);
 
diff --git a/wpimath/src/main/native/include/frc/LinearFilter.h b/wpimath/src/main/native/include/frc/LinearFilter.h
index 51b6a7f266..1c22ba1330 100644
--- a/wpimath/src/main/native/include/frc/LinearFilter.h
+++ b/wpimath/src/main/native/include/frc/LinearFilter.h
@@ -10,8 +10,8 @@
 #include <stdexcept>
 #include <vector>
 
-#include <wpi/ArrayRef.h>
 #include <wpi/circular_buffer.h>
+#include <wpi/span.h>
 
 #include "units/time.h"
 #include "wpimath/MathShared.h"
@@ -77,11 +77,11 @@ class LinearFilter {
    * @param ffGains The "feed forward" or FIR gains.
    * @param fbGains The "feed back" or IIR gains.
    */
-  LinearFilter(wpi::ArrayRef<double> ffGains, wpi::ArrayRef<double> fbGains)
+  LinearFilter(wpi::span<const double> ffGains, wpi::span<const double> fbGains)
       : m_inputs(ffGains.size()),
         m_outputs(fbGains.size()),
-        m_inputGains(ffGains),
-        m_outputGains(fbGains) {
+        m_inputGains(ffGains.begin(), ffGains.end()),
+        m_outputGains(fbGains.begin(), fbGains.end()) {
     for (size_t i = 0; i < ffGains.size(); ++i) {
       m_inputs.emplace_front(0.0);
     }
@@ -103,8 +103,8 @@ class LinearFilter {
    */
   LinearFilter(std::initializer_list<double> ffGains,
                std::initializer_list<double> fbGains)
-      : LinearFilter(wpi::makeArrayRef(ffGains.begin(), ffGains.end()),
-                     wpi::makeArrayRef(fbGains.begin(), fbGains.end())) {}
+      : LinearFilter({ffGains.begin(), ffGains.end()},
+                     {fbGains.begin(), fbGains.end()}) {}
 
   // Static methods to create commonly used filters
   /**
@@ -124,7 +124,7 @@ class LinearFilter {
   static LinearFilter<T> SinglePoleIIR(double timeConstant,
                                        units::second_t period) {
     double gain = std::exp(-period.to<double>() / timeConstant);
-    return LinearFilter(1.0 - gain, -gain);
+    return LinearFilter({1.0 - gain}, {-gain});
   }
 
   /**
diff --git a/wpiutil/src/main/native/cpp/HttpServerConnection.cpp b/wpiutil/src/main/native/cpp/HttpServerConnection.cpp
index 7ef52273e8..716d2af11a 100644
--- a/wpiutil/src/main/native/cpp/HttpServerConnection.cpp
+++ b/wpiutil/src/main/native/cpp/HttpServerConnection.cpp
@@ -7,6 +7,7 @@
 #include "fmt/format.h"
 #include "wpi/SmallString.h"
 #include "wpi/SmallVector.h"
+#include "wpi/SpanExtras.h"
 #include "wpi/StringExtras.h"
 #include "wpi/fmt/raw_ostream.h"
 #include "wpi/raw_uv_ostream.h"
@@ -83,10 +84,9 @@ void HttpServerConnection::BuildHeader(raw_ostream& os, int code,
   os << "\r\n";  // header ends with a blank line
 }
 
-void HttpServerConnection::SendData(ArrayRef<uv::Buffer> bufs,
+void HttpServerConnection::SendData(span<const uv::Buffer> bufs,
                                     bool closeAfter) {
-  m_stream.Write(bufs, [closeAfter, stream = &m_stream](
-                           MutableArrayRef<uv::Buffer> bufs, uv::Error) {
+  m_stream.Write(bufs, [closeAfter, stream = &m_stream](auto bufs, uv::Error) {
     for (auto&& buf : bufs) {
       buf.Deallocate();
     }
@@ -126,9 +126,9 @@ void HttpServerConnection::SendStaticResponse(
   bufs.emplace_back(content);
 
   m_stream.Write(bufs, [closeAfter = !m_keepAlive, stream = &m_stream](
-                           MutableArrayRef<uv::Buffer> bufs, uv::Error) {
+                           auto bufs, uv::Error) {
     // don't deallocate the static content
-    for (auto&& buf : bufs.drop_back()) {
+    for (auto&& buf : wpi::drop_back(bufs)) {
       buf.Deallocate();
     }
     if (closeAfter) {
diff --git a/wpiutil/src/main/native/cpp/HttpUtil.cpp b/wpiutil/src/main/native/cpp/HttpUtil.cpp
index 802432e31e..07aa3523ff 100644
--- a/wpiutil/src/main/native/cpp/HttpUtil.cpp
+++ b/wpiutil/src/main/native/cpp/HttpUtil.cpp
@@ -132,7 +132,7 @@ HttpPath::HttpPath(std::string_view path) {
 }
 
 bool HttpPath::startswith(size_t start,
-                          ArrayRef<std::string_view> match) const {
+                          span<const std::string_view> match) const {
   if (m_pathEnds.size() < (start + match.size())) {
     return false;
   }
diff --git a/wpiutil/src/main/native/cpp/PortForwarder.cpp b/wpiutil/src/main/native/cpp/PortForwarder.cpp
index 797c7c7fdb..a423d48bd3 100644
--- a/wpiutil/src/main/native/cpp/PortForwarder.cpp
+++ b/wpiutil/src/main/native/cpp/PortForwarder.cpp
@@ -36,7 +36,7 @@ static void CopyStream(uv::Stream& in, std::weak_ptr<uv::Stream> outWeak) {
       in.Close();
       return;
     }
-    out->Write(buf2, [](auto bufs, uv::Error) {
+    out->Write({buf2}, [](auto bufs, uv::Error) {
       for (auto buf : bufs) {
         buf.Deallocate();
       }
diff --git a/wpiutil/src/main/native/cpp/TCPConnector_parallel.cpp b/wpiutil/src/main/native/cpp/TCPConnector_parallel.cpp
index dc4f4b106c..ff177bfc6f 100644
--- a/wpiutil/src/main/native/cpp/TCPConnector_parallel.cpp
+++ b/wpiutil/src/main/native/cpp/TCPConnector_parallel.cpp
@@ -24,7 +24,7 @@ using namespace wpi;
 #endif
 
 std::unique_ptr<NetworkStream> TCPConnector::connect_parallel(
-    ArrayRef<std::pair<const char*, int>> servers, Logger& logger,
+    span<const std::pair<const char*, int>> servers, Logger& logger,
     int timeout) {
   if (servers.empty()) {
     return nullptr;
diff --git a/wpiutil/src/main/native/cpp/UDPClient.cpp b/wpiutil/src/main/native/cpp/UDPClient.cpp
index 3e90d47dca..108ef5424c 100644
--- a/wpiutil/src/main/native/cpp/UDPClient.cpp
+++ b/wpiutil/src/main/native/cpp/UDPClient.cpp
@@ -133,7 +133,8 @@ void UDPClient::shutdown() {
   }
 }
 
-int UDPClient::send(ArrayRef<uint8_t> data, std::string_view server, int port) {
+int UDPClient::send(span<const uint8_t> data, std::string_view server,
+                    int port) {
   // server must be a resolvable IP address
   struct sockaddr_in addr;
   std::memset(&addr, 0, sizeof(addr));
diff --git a/wpiutil/src/main/native/cpp/WebSocket.cpp b/wpiutil/src/main/native/cpp/WebSocket.cpp
index e7a38736c7..c44c26adea 100644
--- a/wpiutil/src/main/native/cpp/WebSocket.cpp
+++ b/wpiutil/src/main/native/cpp/WebSocket.cpp
@@ -22,13 +22,13 @@ namespace {
 class WebSocketWriteReq : public uv::WriteReq {
  public:
   explicit WebSocketWriteReq(
-      std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback) {
+      std::function<void(span<uv::Buffer>, uv::Error)> callback) {
     finish.connect([=](uv::Error err) {
-      MutableArrayRef<uv::Buffer> bufs{m_bufs};
-      for (auto&& buf : bufs.slice(0, m_startUser)) {
+      span<uv::Buffer> bufs{m_bufs};
+      for (auto&& buf : bufs.subspan(0, m_startUser)) {
         buf.Deallocate();
       }
-      callback(bufs.slice(m_startUser), err);
+      callback(bufs.subspan(m_startUser), err);
     });
   }
 
@@ -99,7 +99,7 @@ WebSocket::~WebSocket() = default;
 
 std::shared_ptr<WebSocket> WebSocket::CreateClient(
     uv::Stream& stream, std::string_view uri, std::string_view host,
-    ArrayRef<std::string_view> protocols, const ClientOptions& options) {
+    span<const std::string_view> protocols, const ClientOptions& options) {
   auto ws = std::make_shared<WebSocket>(stream, false, private_init{});
   stream.SetData(ws);
   ws->StartClient(uri, host, protocols, options);
@@ -141,7 +141,7 @@ void WebSocket::Terminate(uint16_t code, std::string_view reason) {
 }
 
 void WebSocket::StartClient(std::string_view uri, std::string_view host,
-                            ArrayRef<std::string_view> protocols,
+                            span<const std::string_view> protocols,
                             const ClientOptions& options) {
   // Create client handshake data
   m_clientHandshake = std::make_unique<ClientHandshakeData>();
@@ -317,7 +317,7 @@ void WebSocket::SendClose(uint16_t code, std::string_view reason) {
     raw_uv_ostream os{bufs, 4096};
     const uint8_t codeMsb[] = {static_cast<uint8_t>((code >> 8) & 0xff),
                                static_cast<uint8_t>(code & 0xff)};
-    os << ArrayRef<uint8_t>(codeMsb);
+    os << span{codeMsb};
     os << reason;
   }
   Send(kFlagFin | kOpClose, bufs, [](auto bufs, uv::Error) {
@@ -459,8 +459,7 @@ void WebSocket::HandleIncoming(uv::Buffer& buf, size_t size) {
               m_header[m_headerSize - 4], m_header[m_headerSize - 3],
               m_header[m_headerSize - 2], m_header[m_headerSize - 1]};
           int n = 0;
-          for (uint8_t& ch :
-               MutableArrayRef<uint8_t>{m_payload}.slice(m_frameStart)) {
+          for (uint8_t& ch : span{m_payload}.subspan(m_frameStart)) {
             ch ^= key[n++];
             if (n >= 4) {
               n = 0;
@@ -575,8 +574,8 @@ void WebSocket::HandleIncoming(uv::Buffer& buf, size_t size) {
 }
 
 void WebSocket::Send(
-    uint8_t opcode, ArrayRef<uv::Buffer> data,
-    std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback) {
+    uint8_t opcode, span<const uv::Buffer> data,
+    std::function<void(span<uv::Buffer>, uv::Error)> callback) {
   // If we're not open, emit an error and don't send the data
   if (m_state != OPEN) {
     int err;
@@ -607,7 +606,7 @@ void WebSocket::Send(
     os << static_cast<unsigned char>((m_server ? 0x00 : kFlagMasking) | 126);
     const uint8_t sizeMsb[] = {static_cast<uint8_t>((size >> 8) & 0xff),
                                static_cast<uint8_t>(size & 0xff)};
-    os << ArrayRef<uint8_t>(sizeMsb);
+    os << span{sizeMsb};
   } else {
     os << static_cast<unsigned char>((m_server ? 0x00 : kFlagMasking) | 127);
     const uint8_t sizeMsb[] = {static_cast<uint8_t>((size >> 56) & 0xff),
@@ -618,7 +617,7 @@ void WebSocket::Send(
                                static_cast<uint8_t>((size >> 16) & 0xff),
                                static_cast<uint8_t>((size >> 8) & 0xff),
                                static_cast<uint8_t>(size & 0xff)};
-    os << ArrayRef<uint8_t>(sizeMsb);
+    os << span{sizeMsb};
   }
 
   // clients need to mask the input data
@@ -631,7 +630,7 @@ void WebSocket::Send(
     for (uint8_t& v : key) {
       v = dist(gen);
     }
-    os << ArrayRef<uint8_t>{key, 4};
+    os << span<const uint8_t>{key, 4};
     // copy and mask data
     int n = 0;
     for (auto&& buf : data) {
@@ -645,8 +644,7 @@ void WebSocket::Send(
     req->m_startUser = req->m_bufs.size();
     req->m_bufs.append(data.begin(), data.end());
     // don't send the user bufs as we copied their data
-    m_stream.Write(ArrayRef<uv::Buffer>{req->m_bufs}.slice(0, req->m_startUser),
-                   req);
+    m_stream.Write(span{req->m_bufs}.subspan(0, req->m_startUser), req);
   } else {
     // servers can just send the buffers directly without masking
     req->m_startUser = req->m_bufs.size();
diff --git a/wpiutil/src/main/native/cpp/WebSocketServer.cpp b/wpiutil/src/main/native/cpp/WebSocketServer.cpp
index 45b9fda7b2..1562f3bf04 100644
--- a/wpiutil/src/main/native/cpp/WebSocketServer.cpp
+++ b/wpiutil/src/main/native/cpp/WebSocketServer.cpp
@@ -46,7 +46,7 @@ WebSocketServerHelper::WebSocketServerHelper(HttpParser& req) {
 }
 
 std::pair<bool, std::string_view> WebSocketServerHelper::MatchProtocol(
-    ArrayRef<std::string_view> protocols) {
+    span<const std::string_view> protocols) {
   if (protocols.empty() && m_protocols.empty()) {
     return {true, {}};
   }
@@ -61,7 +61,7 @@ std::pair<bool, std::string_view> WebSocketServerHelper::MatchProtocol(
 }
 
 WebSocketServer::WebSocketServer(uv::Stream& stream,
-                                 ArrayRef<std::string_view> protocols,
+                                 span<const std::string_view> protocols,
                                  ServerOptions options, const private_init&)
     : m_stream{stream},
       m_helper{m_req},
@@ -138,7 +138,7 @@ WebSocketServer::WebSocketServer(uv::Stream& stream,
 }
 
 std::shared_ptr<WebSocketServer> WebSocketServer::Create(
-    uv::Stream& stream, ArrayRef<std::string_view> protocols,
+    uv::Stream& stream, span<const std::string_view> protocols,
     const ServerOptions& options) {
   auto server = std::make_shared<WebSocketServer>(stream, protocols, options,
                                                   private_init{});
diff --git a/wpiutil/src/main/native/cpp/json_binary_reader.cpp b/wpiutil/src/main/native/cpp/json_binary_reader.cpp
index 86d28332cf..cee5e3942a 100644
--- a/wpiutil/src/main/native/cpp/json_binary_reader.cpp
+++ b/wpiutil/src/main/native/cpp/json_binary_reader.cpp
@@ -1384,7 +1384,7 @@ json json::from_cbor(raw_istream& is, const bool strict)
     return binary_reader(is).parse_cbor(strict);
 }
 
-json json::from_cbor(ArrayRef<uint8_t> arr, const bool strict)
+json json::from_cbor(span<const uint8_t> arr, const bool strict)
 {
     raw_mem_istream is(arr);
     return from_cbor(is, strict);
@@ -1395,7 +1395,7 @@ json json::from_msgpack(raw_istream& is, const bool strict)
     return binary_reader(is).parse_msgpack(strict);
 }
 
-json json::from_msgpack(ArrayRef<uint8_t> arr, const bool strict)
+json json::from_msgpack(span<const uint8_t> arr, const bool strict)
 {
     raw_mem_istream is(arr);
     return from_msgpack(is, strict);
@@ -1406,7 +1406,7 @@ json json::from_ubjson(raw_istream& is, const bool strict)
     return binary_reader(is).parse_ubjson(strict);
 }
 
-json json::from_ubjson(ArrayRef<uint8_t> arr, const bool strict)
+json json::from_ubjson(span<const uint8_t> arr, const bool strict)
 {
     raw_mem_istream is(arr);
     return from_ubjson(is, strict);
diff --git a/wpiutil/src/main/native/cpp/json_binary_writer.cpp b/wpiutil/src/main/native/cpp/json_binary_writer.cpp
index 0b6e6b7a16..db23f8dda1 100644
--- a/wpiutil/src/main/native/cpp/json_binary_writer.cpp
+++ b/wpiutil/src/main/native/cpp/json_binary_writer.cpp
@@ -813,7 +813,7 @@ void json::binary_writer::write_number(const NumberType n)
         std::reverse(vec.begin(), vec.end());
     }
 
-    o << ArrayRef<uint8_t>(vec.data(), sizeof(NumberType));
+    o << span{vec.data(), sizeof(NumberType)};
 }
 
 template<typename NumberType, typename std::enable_if<
@@ -1004,7 +1004,7 @@ std::vector<uint8_t> json::to_cbor(const json& j)
     return result;
 }
 
-ArrayRef<uint8_t> json::to_cbor(const json& j, std::vector<uint8_t>& buf)
+span<uint8_t> json::to_cbor(const json& j, std::vector<uint8_t>& buf)
 {
     buf.clear();
     raw_uvector_ostream os(buf);
@@ -1012,7 +1012,7 @@ ArrayRef<uint8_t> json::to_cbor(const json& j, std::vector<uint8_t>& buf)
     return os.array();
 }
 
-ArrayRef<uint8_t> json::to_cbor(const json& j, SmallVectorImpl<uint8_t>& buf)
+span<uint8_t> json::to_cbor(const json& j, SmallVectorImpl<uint8_t>& buf)
 {
     buf.clear();
     raw_usvector_ostream os(buf);
@@ -1033,7 +1033,7 @@ std::vector<uint8_t> json::to_msgpack(const json& j)
     return result;
 }
 
-ArrayRef<uint8_t> json::to_msgpack(const json& j, std::vector<uint8_t>& buf)
+span<uint8_t> json::to_msgpack(const json& j, std::vector<uint8_t>& buf)
 {
     buf.clear();
     raw_uvector_ostream os(buf);
@@ -1041,7 +1041,7 @@ ArrayRef<uint8_t> json::to_msgpack(const json& j, std::vector<uint8_t>& buf)
     return os.array();
 }
 
-ArrayRef<uint8_t> json::to_msgpack(const json& j, SmallVectorImpl<uint8_t>& buf)
+span<uint8_t> json::to_msgpack(const json& j, SmallVectorImpl<uint8_t>& buf)
 {
     buf.clear();
     raw_usvector_ostream os(buf);
@@ -1064,8 +1064,8 @@ std::vector<uint8_t> json::to_ubjson(const json& j,
     return result;
 }
 
-ArrayRef<uint8_t> json::to_ubjson(const json& j, std::vector<uint8_t>& buf,
-                                  const bool use_size, const bool use_type)
+span<uint8_t> json::to_ubjson(const json& j, std::vector<uint8_t>& buf,
+                              const bool use_size, const bool use_type)
 {
     buf.clear();
     raw_uvector_ostream os(buf);
@@ -1073,8 +1073,8 @@ ArrayRef<uint8_t> json::to_ubjson(const json& j, std::vector<uint8_t>& buf,
     return os.array();
 }
 
-ArrayRef<uint8_t> json::to_ubjson(const json& j, SmallVectorImpl<uint8_t>& buf,
-                                  const bool use_size, const bool use_type)
+span<uint8_t> json::to_ubjson(const json& j, SmallVectorImpl<uint8_t>& buf,
+                              const bool use_size, const bool use_type)
 {
     buf.clear();
     raw_usvector_ostream os(buf);
diff --git a/wpiutil/src/main/native/cpp/json_parser.cpp b/wpiutil/src/main/native/cpp/json_parser.cpp
index bae8c118b6..db1ed11d42 100644
--- a/wpiutil/src/main/native/cpp/json_parser.cpp
+++ b/wpiutil/src/main/native/cpp/json_parser.cpp
@@ -1921,11 +1921,11 @@ json json::parse(std::string_view s,
                         const parser_callback_t cb,
                         const bool allow_exceptions)
 {
-    raw_mem_istream is(makeArrayRef(s.data(), s.size()));
+    raw_mem_istream is(span<const char>(s.data(), s.size()));
     return parse(is, cb, allow_exceptions);
 }
 
-json json::parse(ArrayRef<uint8_t> arr,
+json json::parse(span<const uint8_t> arr,
                         const parser_callback_t cb,
                         const bool allow_exceptions)
 {
@@ -1944,11 +1944,11 @@ json json::parse(raw_istream& i,
 
 bool json::accept(std::string_view s)
 {
-    raw_mem_istream is(makeArrayRef(s.data(), s.size()));
+    raw_mem_istream is(span<const char>(s.data(), s.size()));
     return parser(is).accept(true);
 }
 
-bool json::accept(ArrayRef<uint8_t> arr)
+bool json::accept(span<const uint8_t> arr)
 {
     raw_mem_istream is(arr);
     return parser(is).accept(true);
diff --git a/wpiutil/src/main/native/cpp/llvm/ConvertUTFWrapper.cpp b/wpiutil/src/main/native/cpp/llvm/ConvertUTFWrapper.cpp
index bf9b1ad745..db190d0bb6 100644
--- a/wpiutil/src/main/native/cpp/llvm/ConvertUTFWrapper.cpp
+++ b/wpiutil/src/main/native/cpp/llvm/ConvertUTFWrapper.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "wpi/ConvertUTF.h"
+#include "wpi/SmallVector.h"
 #include <string>
 #include <vector>
 
@@ -28,13 +29,13 @@ bool ConvertCodePointToUTF8(unsigned Source, char *&ResultPtr) {
   return true;
 }
 
-bool hasUTF16ByteOrderMark(ArrayRef<char> S) {
+bool hasUTF16ByteOrderMark(span<const char> S) {
   return (S.size() >= 2 &&
           ((S[0] == '\xff' && S[1] == '\xfe') ||
            (S[0] == '\xfe' && S[1] == '\xff')));
 }
 
-bool convertUTF16ToUTF8String(ArrayRef<UTF16> SrcUTF16,
+bool convertUTF16ToUTF8String(span<const UTF16> SrcUTF16,
                               SmallVectorImpl<char> &DstUTF8) {
   assert(DstUTF8.empty());
 
diff --git a/wpiutil/src/main/native/cpp/llvm/SmallPtrSet.cpp b/wpiutil/src/main/native/cpp/llvm/SmallPtrSet.cpp
index 1dab1fcf0e..1b33f4c5ac 100644
--- a/wpiutil/src/main/native/cpp/llvm/SmallPtrSet.cpp
+++ b/wpiutil/src/main/native/cpp/llvm/SmallPtrSet.cpp
@@ -15,6 +15,7 @@
 #include "wpi/SmallPtrSet.h"
 #include "wpi/DenseMapInfo.h"
 #include "wpi/MathExtras.h"
+#include "wpi/MemAlloc.h"
 #include "wpi/ErrorHandling.h"
 #include <algorithm>
 #include <cassert>
diff --git a/wpiutil/src/main/native/cpp/sha1.cpp b/wpiutil/src/main/native/cpp/sha1.cpp
index 5319afb1db..8ec7cb1396 100644
--- a/wpiutil/src/main/native/cpp/sha1.cpp
+++ b/wpiutil/src/main/native/cpp/sha1.cpp
@@ -217,7 +217,7 @@ SHA1::SHA1() {
 }
 
 void SHA1::Update(std::string_view s) {
-  raw_mem_istream is(makeArrayRef(s.data(), s.size()));
+  raw_mem_istream is(span<const char>(s.data(), s.size()));
   Update(is);
 }
 
diff --git a/wpiutil/src/main/native/cpp/uv/Process.cpp b/wpiutil/src/main/native/cpp/uv/Process.cpp
index f41f492a6c..c8d522904c 100644
--- a/wpiutil/src/main/native/cpp/uv/Process.cpp
+++ b/wpiutil/src/main/native/cpp/uv/Process.cpp
@@ -11,7 +11,7 @@
 namespace wpi::uv {
 
 std::shared_ptr<Process> Process::SpawnArray(Loop& loop, std::string_view file,
-                                             ArrayRef<Option> options) {
+                                             span<const Option> options) {
   // convert Option array to libuv structure
   uv_process_options_t coptions;
 
diff --git a/wpiutil/src/main/native/cpp/uv/Stream.cpp b/wpiutil/src/main/native/cpp/uv/Stream.cpp
index 8b03c84297..eafe6372c8 100644
--- a/wpiutil/src/main/native/cpp/uv/Stream.cpp
+++ b/wpiutil/src/main/native/cpp/uv/Stream.cpp
@@ -12,8 +12,8 @@ using namespace wpi::uv;
 namespace {
 class CallbackWriteReq : public WriteReq {
  public:
-  CallbackWriteReq(ArrayRef<Buffer> bufs,
-                   std::function<void(MutableArrayRef<Buffer>, Error)> callback)
+  CallbackWriteReq(span<const Buffer> bufs,
+                   std::function<void(span<Buffer>, Error)> callback)
       : m_bufs{bufs.begin(), bufs.end()} {
     finish.connect([=](Error err) { callback(m_bufs, err); });
   }
@@ -76,7 +76,7 @@ void Stream::StartRead() {
          });
 }
 
-void Stream::Write(ArrayRef<Buffer> bufs,
+void Stream::Write(span<const Buffer> bufs,
                    const std::shared_ptr<WriteReq>& req) {
   if (Invoke(&uv_write, req->GetRaw(), GetRawStream(), bufs.data(), bufs.size(),
              [](uv_write_t* r, int status) {
@@ -91,13 +91,12 @@ void Stream::Write(ArrayRef<Buffer> bufs,
   }
 }
 
-void Stream::Write(
-    ArrayRef<Buffer> bufs,
-    std::function<void(MutableArrayRef<Buffer>, Error)> callback) {
+void Stream::Write(span<const Buffer> bufs,
+                   std::function<void(span<Buffer>, Error)> callback) {
   Write(bufs, std::make_shared<CallbackWriteReq>(bufs, callback));
 }
 
-int Stream::TryWrite(ArrayRef<Buffer> bufs) {
+int Stream::TryWrite(span<const Buffer> bufs) {
   int val = uv_try_write(GetRawStream(), bufs.data(), bufs.size());
   if (val < 0) {
     this->ReportError(val);
diff --git a/wpiutil/src/main/native/cpp/uv/Udp.cpp b/wpiutil/src/main/native/cpp/uv/Udp.cpp
index 130a417e3f..a248d19be6 100644
--- a/wpiutil/src/main/native/cpp/uv/Udp.cpp
+++ b/wpiutil/src/main/native/cpp/uv/Udp.cpp
@@ -17,9 +17,8 @@ using namespace wpi::uv;
 
 class CallbackUdpSendReq : public UdpSendReq {
  public:
-  CallbackUdpSendReq(
-      ArrayRef<Buffer> bufs,
-      std::function<void(MutableArrayRef<Buffer>, Error)> callback)
+  CallbackUdpSendReq(span<const Buffer> bufs,
+                     std::function<void(span<Buffer>, Error)> callback)
       : m_bufs{bufs.begin(), bufs.end()} {
     complete.connect([=](Error err) { callback(m_bufs, err); });
   }
@@ -121,7 +120,7 @@ void Udp::SetMulticastInterface(std::string_view interfaceAddr) {
   Invoke(&uv_udp_set_multicast_interface, GetRaw(), interfaceAddrBuf.c_str());
 }
 
-void Udp::Send(const sockaddr& addr, ArrayRef<Buffer> bufs,
+void Udp::Send(const sockaddr& addr, span<const Buffer> bufs,
                const std::shared_ptr<UdpSendReq>& req) {
   if (Invoke(&uv_udp_send, req->GetRaw(), GetRaw(), bufs.data(), bufs.size(),
              &addr, [](uv_udp_send_t* r, int status) {
@@ -136,12 +135,13 @@ void Udp::Send(const sockaddr& addr, ArrayRef<Buffer> bufs,
   }
 }
 
-void Udp::Send(const sockaddr& addr, ArrayRef<Buffer> bufs,
-               std::function<void(MutableArrayRef<Buffer>, Error)> callback) {
+void Udp::Send(const sockaddr& addr, span<const Buffer> bufs,
+               std::function<void(span<Buffer>, Error)> callback) {
   Send(addr, bufs, std::make_shared<CallbackUdpSendReq>(bufs, callback));
 }
 
-void Udp::Send(ArrayRef<Buffer> bufs, const std::shared_ptr<UdpSendReq>& req) {
+void Udp::Send(span<const Buffer> bufs,
+               const std::shared_ptr<UdpSendReq>& req) {
   if (Invoke(&uv_udp_send, req->GetRaw(), GetRaw(), bufs.data(), bufs.size(),
              nullptr, [](uv_udp_send_t* r, int status) {
                auto& h = *static_cast<UdpSendReq*>(r->data);
@@ -155,8 +155,8 @@ void Udp::Send(ArrayRef<Buffer> bufs, const std::shared_ptr<UdpSendReq>& req) {
   }
 }
 
-void Udp::Send(ArrayRef<Buffer> bufs,
-               std::function<void(MutableArrayRef<Buffer>, Error)> callback) {
+void Udp::Send(span<const Buffer> bufs,
+               std::function<void(span<Buffer>, Error)> callback) {
   Send(bufs, std::make_shared<CallbackUdpSendReq>(bufs, callback));
 }
 
diff --git a/wpiutil/src/main/native/include/wpi/ArrayRef.h b/wpiutil/src/main/native/include/wpi/ArrayRef.h
deleted file mode 100644
index 754d0d3403..0000000000
--- a/wpiutil/src/main/native/include/wpi/ArrayRef.h
+++ /dev/null
@@ -1,586 +0,0 @@
-//===- ArrayRef.h - Array Reference Wrapper ---------------------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef WPIUTIL_WPI_ARRAYREF_H
-#define WPIUTIL_WPI_ARRAYREF_H
-
-#include "wpi/Hashing.h"
-#include "wpi/SmallVector.h"
-#include "wpi/STLExtras.h"
-#include "wpi/Compiler.h"
-#include "wpi/span.h"
-#include <algorithm>
-#include <array>
-#include <cassert>
-#include <cstddef>
-#include <initializer_list>
-#include <iterator>
-#include <memory>
-#include <optional>
-#include <type_traits>
-#include <vector>
-#if __cplusplus >= 202002L && __has_include(<span>)
-#include <span>
-#endif
-
-namespace wpi {
-
-  /// ArrayRef - Represent a constant reference to an array (0 or more elements
-  /// consecutively in memory), i.e. a start pointer and a length.  It allows
-  /// various APIs to take consecutive elements easily and conveniently.
-  ///
-  /// This class does not own the underlying data, it is expected to be used in
-  /// situations where the data resides in some other buffer, whose lifetime
-  /// extends past that of the ArrayRef. For this reason, it is not in general
-  /// safe to store an ArrayRef.
-  ///
-  /// This is intended to be trivially copyable, so it should be passed by
-  /// value.
-  template<typename T>
-  class LLVM_NODISCARD ArrayRef {
-  public:
-    using iterator = const T *;
-    using const_iterator = const T *;
-    using size_type = size_t;
-    using reverse_iterator = std::reverse_iterator<iterator>;
-    using value_type = T;
-
-  private:
-    /// The start of the array, in an external buffer.
-    const T *Data = nullptr;
-
-    /// The number of elements.
-    size_type Length = 0;
-
-  public:
-    /// @name Constructors
-    /// @{
-
-    /// Construct an empty ArrayRef.
-    /*implicit*/ ArrayRef() = default;
-
-    /// Construct an empty ArrayRef from nullopt.
-    /*implicit*/ ArrayRef(std::nullopt_t) {}
-
-    /// Construct an ArrayRef from a single element.
-    /*implicit*/ ArrayRef(const T &OneElt)
-      : Data(&OneElt), Length(1) {}
-
-    /// Construct an ArrayRef from a pointer and length.
-    /*implicit*/ ArrayRef(const T *data, size_t length)
-      : Data(data), Length(length) {}
-
-    /// Construct an ArrayRef from a range.
-    ArrayRef(const T *begin, const T *end)
-      : Data(begin), Length(end - begin) {}
-
-    /// Construct an ArrayRef from a SmallVector. This is templated in order to
-    /// avoid instantiating SmallVectorTemplateCommon<T> whenever we
-    /// copy-construct an ArrayRef.
-    template<typename U>
-    /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
-      : Data(Vec.data()), Length(Vec.size()) {
-    }
-
-    /// Construct an ArrayRef from a std::vector.
-    template<typename A>
-    /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
-      : Data(Vec.data()), Length(Vec.size()) {}
-
-    /// Construct an ArrayRef from a std::array
-    template <size_t N>
-    /*implicit*/ constexpr ArrayRef(const std::array<T, N> &Arr)
-        : Data(Arr.data()), Length(N) {}
-
-    /// Construct an ArrayRef from a C array.
-    template <size_t N>
-    /*implicit*/ constexpr ArrayRef(const T (&Arr)[N]) : Data(Arr), Length(N) {}
-
-    /// Construct an ArrayRef<const T*> from ArrayRef<T*>. This uses SFINAE to
-    /// ensure that only ArrayRefs of pointers can be converted.
-    template <typename U>
-    ArrayRef(
-        const ArrayRef<U *> &A,
-        typename std::enable_if<
-           std::is_convertible<U *const *, T const *>::value>::type * = nullptr)
-      : Data(A.data()), Length(A.size()) {}
-
-    /// Construct an ArrayRef<const T*> from a SmallVector<T*>. This is
-    /// templated in order to avoid instantiating SmallVectorTemplateCommon<T>
-    /// whenever we copy-construct an ArrayRef.
-    template<typename U, typename DummyT>
-    /*implicit*/ ArrayRef(
-      const SmallVectorTemplateCommon<U *, DummyT> &Vec,
-      typename std::enable_if<
-          std::is_convertible<U *const *, T const *>::value>::type * = nullptr)
-      : Data(Vec.data()), Length(Vec.size()) {
-    }
-
-    /// Construct an ArrayRef<const T*> from std::vector<T*>. This uses SFINAE
-    /// to ensure that only vectors of pointers can be converted.
-    template<typename U, typename A>
-    ArrayRef(const std::vector<U *, A> &Vec,
-             typename std::enable_if<
-                 std::is_convertible<U *const *, T const *>::value>::type* = 0)
-      : Data(Vec.data()), Length(Vec.size()) {}
-
-#ifdef __cpp_lib_span
-    /// Construct an ArrayRef from std::span
-    /*implicit*/ ArrayRef(std::span<T> Span)
-        : Data(Span.data()), Length(Span.size()) {}
-
-    /// Construct an ArrayRef from std::span
-    /*implicit*/ ArrayRef(std::span<const T> Span)
-        : Data(Span.data()), Length(Span.size()) {}
-#endif
-
-    /// Construct an ArrayRef from wpi::span
-    /*implicit*/ ArrayRef(span<T> Span)
-        : Data(Span.data()), Length(Span.size()) {}
-
-    /// Construct an ArrayRef from wpi::span
-    /*implicit*/ ArrayRef(span<const T> Span)
-        : Data(Span.data()), Length(Span.size()) {}
-
-    /// @}
-    /// @name Simple Operations
-    /// @{
-
-    iterator begin() const { return Data; }
-    iterator end() const { return Data + Length; }
-
-    reverse_iterator rbegin() const { return reverse_iterator(end()); }
-    reverse_iterator rend() const { return reverse_iterator(begin()); }
-
-    /// empty - Check if the array is empty.
-    bool empty() const { return Length == 0; }
-
-    const T *data() const { return Data; }
-
-    /// size - Get the array size.
-    size_t size() const { return Length; }
-
-    /// front - Get the first element.
-    const T &front() const {
-      assert(!empty());
-      return Data[0];
-    }
-
-    /// back - Get the last element.
-    const T &back() const {
-      assert(!empty());
-      return Data[Length-1];
-    }
-
-    // copy - Allocate copy in Allocator and return ArrayRef<T> to it.
-    template <typename Allocator> ArrayRef<T> copy(Allocator &A) {
-      T *Buff = A.template Allocate<T>(Length);
-      std::uninitialized_copy(begin(), end(), Buff);
-      return ArrayRef<T>(Buff, Length);
-    }
-
-    /// equals - Check for element-wise equality.
-    bool equals(ArrayRef RHS) const {
-      if (Length != RHS.Length)
-        return false;
-      return std::equal(begin(), end(), RHS.begin());
-    }
-
-    /// slice(n, m) - Chop off the first N elements of the array, and keep M
-    /// elements in the array.
-    ArrayRef<T> slice(size_t N, size_t M) const {
-      assert(N+M <= size() && "Invalid specifier");
-      return ArrayRef<T>(data()+N, M);
-    }
-
-    /// slice(n) - Chop off the first N elements of the array.
-    ArrayRef<T> slice(size_t N) const { return slice(N, size() - N); }
-
-    /// Drop the first \p N elements of the array.
-    ArrayRef<T> drop_front(size_t N = 1) const {
-      assert(size() >= N && "Dropping more elements than exist");
-      return slice(N, size() - N);
-    }
-
-    /// Drop the last \p N elements of the array.
-    ArrayRef<T> drop_back(size_t N = 1) const {
-      assert(size() >= N && "Dropping more elements than exist");
-      return slice(0, size() - N);
-    }
-
-    /// Return a copy of *this with the first N elements satisfying the
-    /// given predicate removed.
-    template <class PredicateT> ArrayRef<T> drop_while(PredicateT Pred) const {
-      return ArrayRef<T>(find_if_not(*this, Pred), end());
-    }
-
-    /// Return a copy of *this with the first N elements not satisfying
-    /// the given predicate removed.
-    template <class PredicateT> ArrayRef<T> drop_until(PredicateT Pred) const {
-      return ArrayRef<T>(find_if(*this, Pred), end());
-    }
-
-    /// Return a copy of *this with only the first \p N elements.
-    ArrayRef<T> take_front(size_t N = 1) const {
-      if (N >= size())
-        return *this;
-      return drop_back(size() - N);
-    }
-
-    /// Return a copy of *this with only the last \p N elements.
-    ArrayRef<T> take_back(size_t N = 1) const {
-      if (N >= size())
-        return *this;
-      return drop_front(size() - N);
-    }
-
-    /// Return the first N elements of this Array that satisfy the given
-    /// predicate.
-    template <class PredicateT> ArrayRef<T> take_while(PredicateT Pred) const {
-      return ArrayRef<T>(begin(), find_if_not(*this, Pred));
-    }
-
-    /// Return the first N elements of this Array that don't satisfy the
-    /// given predicate.
-    template <class PredicateT> ArrayRef<T> take_until(PredicateT Pred) const {
-      return ArrayRef<T>(begin(), find_if(*this, Pred));
-    }
-
-    /// @}
-    /// @name Operator Overloads
-    /// @{
-    const T &operator[](size_t Index) const {
-      assert(Index < Length && "Invalid index!");
-      return Data[Index];
-    }
-
-    /// Disallow accidental assignment from a temporary.
-    ///
-    /// The declaration here is extra complicated so that "arrayRef = {}"
-    /// continues to select the move assignment operator.
-    template <typename U>
-    typename std::enable_if<std::is_same<U, T>::value, ArrayRef<T>>::type &
-    operator=(U &&Temporary) = delete;
-
-    /// Disallow accidental assignment from a temporary.
-    ///
-    /// The declaration here is extra complicated so that "arrayRef = {}"
-    /// continues to select the move assignment operator.
-    template <typename U>
-    typename std::enable_if<std::is_same<U, T>::value, ArrayRef<T>>::type &
-    operator=(std::initializer_list<U>) = delete;
-
-    /// @}
-    /// @name Expensive Operations
-    /// @{
-    std::vector<T> vec() const {
-      return std::vector<T>(Data, Data+Length);
-    }
-
-    /// @}
-    /// @name Conversion operators
-    /// @{
-    operator std::vector<T>() const {
-      return std::vector<T>(Data, Data+Length);
-    }
-
-#ifdef __cpp_lib_span
-    operator std::span<const T>() const {
-      return std::span<const T>(Data, Length);
-    }
-#endif
-
-    operator span<const T>() const {
-      return span<const T>(Data, Length);
-    }
-    /// @}
-  };
-
-  /// MutableArrayRef - Represent a mutable reference to an array (0 or more
-  /// elements consecutively in memory), i.e. a start pointer and a length.  It
-  /// allows various APIs to take and modify consecutive elements easily and
-  /// conveniently.
-  ///
-  /// This class does not own the underlying data, it is expected to be used in
-  /// situations where the data resides in some other buffer, whose lifetime
-  /// extends past that of the MutableArrayRef. For this reason, it is not in
-  /// general safe to store a MutableArrayRef.
-  ///
-  /// This is intended to be trivially copyable, so it should be passed by
-  /// value.
-  template<typename T>
-  class LLVM_NODISCARD MutableArrayRef : public ArrayRef<T> {
-  public:
-    using iterator = T *;
-    using reverse_iterator = std::reverse_iterator<iterator>;
-
-    /// Construct an empty MutableArrayRef.
-    /*implicit*/ MutableArrayRef() = default;
-
-    /// Construct an empty MutableArrayRef from nullopt.
-    /*implicit*/ MutableArrayRef(std::nullopt_t) : ArrayRef<T>() {}
-
-    /// Construct an MutableArrayRef from a single element.
-    /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}
-
-    /// Construct an MutableArrayRef from a pointer and length.
-    /*implicit*/ MutableArrayRef(T *data, size_t length)
-      : ArrayRef<T>(data, length) {}
-
-    /// Construct an MutableArrayRef from a range.
-    MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}
-
-    /// Construct an MutableArrayRef from a SmallVector.
-    /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
-    : ArrayRef<T>(Vec) {}
-
-    /// Construct a MutableArrayRef from a std::vector.
-    /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
-    : ArrayRef<T>(Vec) {}
-
-    /// Construct an ArrayRef from a std::array
-    template <size_t N>
-    /*implicit*/ constexpr MutableArrayRef(std::array<T, N> &Arr)
-        : ArrayRef<T>(Arr) {}
-
-    /// Construct an MutableArrayRef from a C array.
-    template <size_t N>
-    /*implicit*/ constexpr MutableArrayRef(T (&Arr)[N]) : ArrayRef<T>(Arr) {}
-
-#ifdef __cpp_lib_span
-    /// Construct an ArrayRef from std::span
-    /*implicit*/ MutableArrayRef(std::span<T> Span) : ArrayRef<T>(Span) {}
-#endif
-
-    /// Construct an ArrayRef from wpi::span
-    /*implicit*/ MutableArrayRef(span<T> Span) : ArrayRef<T>(Span) {}
-
-    T *data() const { return const_cast<T*>(ArrayRef<T>::data()); }
-
-    iterator begin() const { return data(); }
-    iterator end() const { return data() + this->size(); }
-
-    reverse_iterator rbegin() const { return reverse_iterator(end()); }
-    reverse_iterator rend() const { return reverse_iterator(begin()); }
-
-    /// front - Get the first element.
-    T &front() const {
-      assert(!this->empty());
-      return data()[0];
-    }
-
-    /// back - Get the last element.
-    T &back() const {
-      assert(!this->empty());
-      return data()[this->size()-1];
-    }
-
-    /// slice(n, m) - Chop off the first N elements of the array, and keep M
-    /// elements in the array.
-    MutableArrayRef<T> slice(size_t N, size_t M) const {
-      assert(N + M <= this->size() && "Invalid specifier");
-      return MutableArrayRef<T>(this->data() + N, M);
-    }
-
-    /// slice(n) - Chop off the first N elements of the array.
-    MutableArrayRef<T> slice(size_t N) const {
-      return slice(N, this->size() - N);
-    }
-
-    /// Drop the first \p N elements of the array.
-    MutableArrayRef<T> drop_front(size_t N = 1) const {
-      assert(this->size() >= N && "Dropping more elements than exist");
-      return slice(N, this->size() - N);
-    }
-
-    MutableArrayRef<T> drop_back(size_t N = 1) const {
-      assert(this->size() >= N && "Dropping more elements than exist");
-      return slice(0, this->size() - N);
-    }
-
-    /// Return a copy of *this with the first N elements satisfying the
-    /// given predicate removed.
-    template <class PredicateT>
-    MutableArrayRef<T> drop_while(PredicateT Pred) const {
-      return MutableArrayRef<T>(find_if_not(*this, Pred), end());
-    }
-
-    /// Return a copy of *this with the first N elements not satisfying
-    /// the given predicate removed.
-    template <class PredicateT>
-    MutableArrayRef<T> drop_until(PredicateT Pred) const {
-      return MutableArrayRef<T>(find_if(*this, Pred), end());
-    }
-
-    /// Return a copy of *this with only the first \p N elements.
-    MutableArrayRef<T> take_front(size_t N = 1) const {
-      if (N >= this->size())
-        return *this;
-      return drop_back(this->size() - N);
-    }
-
-    /// Return a copy of *this with only the last \p N elements.
-    MutableArrayRef<T> take_back(size_t N = 1) const {
-      if (N >= this->size())
-        return *this;
-      return drop_front(this->size() - N);
-    }
-
-    /// Return the first N elements of this Array that satisfy the given
-    /// predicate.
-    template <class PredicateT>
-    MutableArrayRef<T> take_while(PredicateT Pred) const {
-      return MutableArrayRef<T>(begin(), find_if_not(*this, Pred));
-    }
-
-    /// Return the first N elements of this Array that don't satisfy the
-    /// given predicate.
-    template <class PredicateT>
-    MutableArrayRef<T> take_until(PredicateT Pred) const {
-      return MutableArrayRef<T>(begin(), find_if(*this, Pred));
-    }
-
-    /// @}
-    /// @name Operator Overloads
-    /// @{
-    T &operator[](size_t Index) const {
-      assert(Index < this->size() && "Invalid index!");
-      return data()[Index];
-    }
-
-#ifdef __cpp_lib_span
-    operator std::span<T>() const {
-      return std::span<T>(data(), this->size());
-    }
-#endif
-
-    operator span<T>() const {
-      return span<T>(data(), this->size());
-    }
-  };
-
-  /// This is a MutableArrayRef that owns its array.
-  template <typename T> class OwningArrayRef : public MutableArrayRef<T> {
-  public:
-    OwningArrayRef() = default;
-    OwningArrayRef(size_t Size) : MutableArrayRef<T>(new T[Size], Size) {}
-
-    OwningArrayRef(ArrayRef<T> Data)
-        : MutableArrayRef<T>(new T[Data.size()], Data.size()) {
-      std::copy(Data.begin(), Data.end(), this->begin());
-    }
-
-    OwningArrayRef(OwningArrayRef &&Other) { *this = Other; }
-
-    OwningArrayRef &operator=(OwningArrayRef &&Other) {
-      delete[] this->data();
-      this->MutableArrayRef<T>::operator=(Other);
-      Other.MutableArrayRef<T>::operator=(MutableArrayRef<T>());
-      return *this;
-    }
-
-    ~OwningArrayRef() { delete[] this->data(); }
-  };
-
-  /// @name ArrayRef Convenience constructors
-  /// @{
-
-  /// Construct an ArrayRef from a single element.
-  template<typename T>
-  ArrayRef<T> makeArrayRef(const T &OneElt) {
-    return OneElt;
-  }
-
-  /// Construct an ArrayRef from a pointer and length.
-  template<typename T>
-  ArrayRef<T> makeArrayRef(const T *data, size_t length) {
-    return ArrayRef<T>(data, length);
-  }
-
-  /// Construct an ArrayRef from a range.
-  template<typename T>
-  ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
-    return ArrayRef<T>(begin, end);
-  }
-
-  /// Construct an ArrayRef from a SmallVector.
-  template <typename T>
-  ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
-    return Vec;
-  }
-
-  /// Construct an ArrayRef from a SmallVector.
-  template <typename T, unsigned N>
-  ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
-    return Vec;
-  }
-
-  /// Construct an ArrayRef from a std::vector.
-  template<typename T>
-  ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
-    return Vec;
-  }
-
-  /// Construct an ArrayRef from an ArrayRef (no-op) (const)
-  template <typename T> ArrayRef<T> makeArrayRef(const ArrayRef<T> &Vec) {
-    return Vec;
-  }
-
-  /// Construct an ArrayRef from an ArrayRef (no-op)
-  template <typename T> ArrayRef<T> &makeArrayRef(ArrayRef<T> &Vec) {
-    return Vec;
-  }
-
-  /// Construct an ArrayRef from a C array.
-  template<typename T, size_t N>
-  ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
-    return ArrayRef<T>(Arr);
-  }
-
-  /// Construct a MutableArrayRef from a single element.
-  template<typename T>
-  MutableArrayRef<T> makeMutableArrayRef(T &OneElt) {
-    return OneElt;
-  }
-
-  /// Construct a MutableArrayRef from a pointer and length.
-  template<typename T>
-  MutableArrayRef<T> makeMutableArrayRef(T *data, size_t length) {
-    return MutableArrayRef<T>(data, length);
-  }
-
-  /// @}
-  /// @name ArrayRef Comparison Operators
-  /// @{
-
-  template<typename T>
-  inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
-    return LHS.equals(RHS);
-  }
-
-  template<typename T>
-  inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
-    return !(LHS == RHS);
-  }
-
-  /// @}
-
-  // ArrayRefs can be treated like a POD type.
-  template <typename T> struct isPodLike;
-  template <typename T> struct isPodLike<ArrayRef<T>> {
-    static const bool value = true;
-  };
-
-  template <typename T> hash_code hash_value(ArrayRef<T> S) {
-    return hash_combine_range(S.begin(), S.end());
-  }
-
-} // end namespace wpi
-
-#endif // LLVM_ADT_ARRAYREF_H
diff --git a/wpiutil/src/main/native/include/wpi/ConvertUTF.h b/wpiutil/src/main/native/include/wpi/ConvertUTF.h
index 99aac6a89b..aa113b1526 100644
--- a/wpiutil/src/main/native/include/wpi/ConvertUTF.h
+++ b/wpiutil/src/main/native/include/wpi/ConvertUTF.h
@@ -90,7 +90,7 @@
 #ifndef LLVM_SUPPORT_CONVERTUTF_H
 #define LLVM_SUPPORT_CONVERTUTF_H
 
-#include "wpi/ArrayRef.h"
+#include "wpi/span.h"
 
 #include <cstddef>
 #include <string>
@@ -102,6 +102,9 @@
 
 namespace wpi {
 
+template <typename T>
+class SmallVectorImpl;
+
 /* ---------------------------------------------------------------------
     The following 4 definitions are compiler-specific.
     The C standard does not guarantee that wchar_t has at least
@@ -228,14 +231,14 @@ static inline ConversionResult convertUTF8Sequence(const UTF8 **source,
  * Returns true if a blob of text starts with a UTF-16 big or little endian byte
  * order mark.
  */
-bool hasUTF16ByteOrderMark(ArrayRef<char> SrcBytes);
+bool hasUTF16ByteOrderMark(span<const char> SrcBytes);
 
 /**
  * Converts a UTF-16 string into a UTF-8 string.
  *
  * \returns true on success
  */
-bool convertUTF16ToUTF8String(ArrayRef<UTF16> SrcUTF16,
+bool convertUTF16ToUTF8String(span<const UTF16> SrcUTF16,
                               SmallVectorImpl<char> &DstUTF8);
 
 /**
diff --git a/wpiutil/src/main/native/include/wpi/DenseMapInfo.h b/wpiutil/src/main/native/include/wpi/DenseMapInfo.h
index f6b1d4b7c0..b6525a32c4 100644
--- a/wpiutil/src/main/native/include/wpi/DenseMapInfo.h
+++ b/wpiutil/src/main/native/include/wpi/DenseMapInfo.h
@@ -14,9 +14,9 @@
 #ifndef WPIUTIL_WPI_DENSEMAPINFO_H
 #define WPIUTIL_WPI_DENSEMAPINFO_H
 
-#include "wpi/ArrayRef.h"
 #include "wpi/Hashing.h"
 #include "wpi/PointerLikeTypeTraits.h"
+#include "wpi/span.h"
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
@@ -234,26 +234,26 @@ template <> struct DenseMapInfo<std::string_view> {
   }
 };
 
-// Provide DenseMapInfo for ArrayRefs.
-template <typename T> struct DenseMapInfo<ArrayRef<T>> {
-  static inline ArrayRef<T> getEmptyKey() {
-    return ArrayRef<T>(reinterpret_cast<const T *>(~static_cast<uintptr_t>(0)),
-                       size_t(0));
+// Provide DenseMapInfo for spans.
+template <typename T> struct DenseMapInfo<span<T>> {
+  static inline span<T> getEmptyKey() {
+    return span<T>(reinterpret_cast<const T *>(~static_cast<uintptr_t>(0)),
+                   size_t(0));
   }
 
-  static inline ArrayRef<T> getTombstoneKey() {
-    return ArrayRef<T>(reinterpret_cast<const T *>(~static_cast<uintptr_t>(1)),
-                       size_t(0));
+  static inline span<T> getTombstoneKey() {
+    return span<T>(reinterpret_cast<const T *>(~static_cast<uintptr_t>(1)),
+                   size_t(0));
   }
 
-  static unsigned getHashValue(ArrayRef<T> Val) {
+  static unsigned getHashValue(span<T> Val) {
     assert(Val.data() != getEmptyKey().data() && "Cannot hash the empty key!");
     assert(Val.data() != getTombstoneKey().data() &&
            "Cannot hash the tombstone key!");
     return (unsigned)(hash_value(Val));
   }
 
-  static bool isEqual(ArrayRef<T> LHS, ArrayRef<T> RHS) {
+  static bool isEqual(span<T> LHS, span<T> RHS) {
     if (RHS.data() == getEmptyKey().data())
       return LHS.data() == getEmptyKey().data();
     if (RHS.data() == getTombstoneKey().data())
diff --git a/wpiutil/src/main/native/include/wpi/HttpServerConnection.h b/wpiutil/src/main/native/include/wpi/HttpServerConnection.h
index b882dead51..29006b178e 100644
--- a/wpiutil/src/main/native/include/wpi/HttpServerConnection.h
+++ b/wpiutil/src/main/native/include/wpi/HttpServerConnection.h
@@ -8,8 +8,8 @@
 #include <memory>
 #include <string_view>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/HttpParser.h"
+#include "wpi/span.h"
 #include "wpi/uv/Stream.h"
 
 namespace wpi {
@@ -78,7 +78,7 @@ class HttpServerConnection {
    *             is desired, call m_stream.Write() directly instead.
    * @param closeAfter close the connection after the write completes
    */
-  void SendData(ArrayRef<uv::Buffer> bufs, bool closeAfter = false);
+  void SendData(span<const uv::Buffer> bufs, bool closeAfter = false);
 
   /**
    * Send HTTP response, along with other header information like mimetype.
diff --git a/wpiutil/src/main/native/include/wpi/HttpUtil.h b/wpiutil/src/main/native/include/wpi/HttpUtil.h
index b0c97f88b7..b10d127a82 100644
--- a/wpiutil/src/main/native/include/wpi/HttpUtil.h
+++ b/wpiutil/src/main/native/include/wpi/HttpUtil.h
@@ -13,7 +13,6 @@
 #include <utility>
 #include <vector>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/NetworkStream.h"
 #include "wpi/SmallString.h"
 #include "wpi/SmallVector.h"
@@ -21,6 +20,7 @@
 #include "wpi/raw_istream.h"
 #include "wpi/raw_socket_istream.h"
 #include "wpi/raw_socket_ostream.h"
+#include "wpi/span.h"
 
 namespace wpi {
 
@@ -143,14 +143,12 @@ class HttpPath {
    * @return True if path equals match list
    */
   bool equals(std::initializer_list<std::string_view> match) const {
-    return equals(0, makeArrayRef(match.begin(), match.end()));
+    return equals(0, {match.begin(), match.end()});
   }
-  bool equals(ArrayRef<std::string_view> match) const {
+  bool equals(span<const std::string_view> match) const {
     return equals(0, match);
   }
-  bool equals(std::string_view match) const {
-    return equals(0, makeArrayRef(match));
-  }
+  bool equals(std::string_view match) const { return equals(0, {match}); }
 
   /**
    * Returns true if the elements of the path starting at the "start" element
@@ -162,16 +160,16 @@ class HttpPath {
    */
   bool equals(size_t start,
               std::initializer_list<std::string_view> match) const {
-    return equals(start, makeArrayRef(match.begin(), match.end()));
+    return equals(start, {match.begin(), match.end()});
   }
-  bool equals(size_t start, ArrayRef<std::string_view> match) const {
+  bool equals(size_t start, span<const std::string_view> match) const {
     if (m_pathEnds.size() != (start + match.size())) {
       return false;
     }
     return startswith(start, match);
   }
   bool equals(size_t start, std::string_view match) const {
-    return equals(start, makeArrayRef(match));
+    return equals(start, {match});
   }
 
   /**
@@ -182,13 +180,13 @@ class HttpPath {
    * @return True if path starts with match list
    */
   bool startswith(std::initializer_list<std::string_view> match) const {
-    return startswith(0, makeArrayRef(match.begin(), match.end()));
+    return startswith(0, {match.begin(), match.end()});
   }
-  bool startswith(ArrayRef<std::string_view> match) const {
+  bool startswith(span<const std::string_view> match) const {
     return startswith(0, match);
   }
   bool startswith(std::string_view match) const {
-    return startswith(0, makeArrayRef(match));
+    return startswith(0, {match});
   }
 
   /**
@@ -201,13 +199,13 @@ class HttpPath {
    */
   bool startswith(size_t start,
                   std::initializer_list<std::string_view> match) const {
-    return startswith(start, makeArrayRef(match.begin(), match.end()));
+    return startswith(start, {match.begin(), match.end()});
   }
 
-  bool startswith(size_t start, ArrayRef<std::string_view> match) const;
+  bool startswith(size_t start, span<const std::string_view> match) const;
 
   bool startswith(size_t start, std::string_view match) const {
-    return startswith(start, makeArrayRef(match));
+    return startswith(start, {match});
   }
 
   /**
@@ -240,45 +238,43 @@ class HttpPathRef {
   size_t size() const { return m_path ? m_path->size() - m_start : 0; }
 
   bool equals(std::initializer_list<std::string_view> match) const {
-    return equals(0, makeArrayRef(match.begin(), match.end()));
+    return equals(0, {match.begin(), match.end()});
   }
-  bool equals(ArrayRef<std::string_view> match) const {
+  bool equals(span<const std::string_view> match) const {
     return equals(0, match);
   }
-  bool equals(std::string_view match) const {
-    return equals(0, makeArrayRef(match));
-  }
+  bool equals(std::string_view match) const { return equals(0, {match}); }
 
   bool equals(size_t start,
               std::initializer_list<std::string_view> match) const {
-    return equals(start, makeArrayRef(match.begin(), match.end()));
+    return equals(start, {match.begin(), match.end()});
   }
-  bool equals(size_t start, ArrayRef<std::string_view> match) const {
+  bool equals(size_t start, span<const std::string_view> match) const {
     return m_path ? m_path->equals(m_start + start, match) : false;
   }
   bool equals(size_t start, std::string_view match) const {
-    return equals(start, makeArrayRef(match));
+    return equals(start, {match});
   }
 
   bool startswith(std::initializer_list<std::string_view> match) const {
-    return startswith(0, makeArrayRef(match.begin(), match.end()));
+    return startswith(0, {match.begin(), match.end()});
   }
-  bool startswith(ArrayRef<std::string_view> match) const {
+  bool startswith(span<const std::string_view> match) const {
     return startswith(0, match);
   }
   bool startswith(std::string_view match) const {
-    return startswith(0, makeArrayRef(match));
+    return startswith(0, {match});
   }
 
   bool startswith(size_t start,
                   std::initializer_list<std::string_view> match) const {
-    return startswith(start, makeArrayRef(match.begin(), match.end()));
+    return startswith(start, {match.begin(), match.end()});
   }
-  bool startswith(size_t start, ArrayRef<std::string_view> match) const {
+  bool startswith(size_t start, span<const std::string_view> match) const {
     return m_path ? m_path->startswith(m_start + start, match) : false;
   }
   bool startswith(size_t start, std::string_view match) const {
-    return startswith(start, makeArrayRef(match));
+    return startswith(start, {match});
   }
 
   std::string_view operator[](size_t n) const {
diff --git a/wpiutil/src/main/native/include/wpi/HttpWebSocketServerConnection.h b/wpiutil/src/main/native/include/wpi/HttpWebSocketServerConnection.h
index a59375d2e6..d89b61f0a9 100644
--- a/wpiutil/src/main/native/include/wpi/HttpWebSocketServerConnection.h
+++ b/wpiutil/src/main/native/include/wpi/HttpWebSocketServerConnection.h
@@ -10,11 +10,11 @@
 #include <string>
 #include <string_view>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/HttpServerConnection.h"
 #include "wpi/SmallVector.h"
 #include "wpi/WebSocket.h"
 #include "wpi/WebSocketServer.h"
+#include "wpi/span.h"
 #include "wpi/uv/Stream.h"
 
 namespace wpi {
@@ -36,7 +36,7 @@ class HttpWebSocketServerConnection
    * @param protocols Acceptable subprotocols
    */
   HttpWebSocketServerConnection(std::shared_ptr<uv::Stream> stream,
-                                ArrayRef<std::string_view> protocols);
+                                span<const std::string_view> protocols);
 
   /**
    * Constructor.
@@ -47,8 +47,8 @@ class HttpWebSocketServerConnection
   HttpWebSocketServerConnection(
       std::shared_ptr<uv::Stream> stream,
       std::initializer_list<std::string_view> protocols)
-      : HttpWebSocketServerConnection(
-            stream, makeArrayRef(protocols.begin(), protocols.end())) {}
+      : HttpWebSocketServerConnection(stream,
+                                      {protocols.begin(), protocols.end()}) {}
 
  protected:
   /**
diff --git a/wpiutil/src/main/native/include/wpi/HttpWebSocketServerConnection.inc b/wpiutil/src/main/native/include/wpi/HttpWebSocketServerConnection.inc
index 3e084e9240..68b9f2d91d 100644
--- a/wpiutil/src/main/native/include/wpi/HttpWebSocketServerConnection.inc
+++ b/wpiutil/src/main/native/include/wpi/HttpWebSocketServerConnection.inc
@@ -13,7 +13,7 @@ namespace wpi {
 
 template <typename Derived>
 HttpWebSocketServerConnection<Derived>::HttpWebSocketServerConnection(
-    std::shared_ptr<uv::Stream> stream, ArrayRef<std::string_view> protocols)
+    std::shared_ptr<uv::Stream> stream, span<const std::string_view> protocols)
     : HttpServerConnection{stream},
       m_helper{m_request},
       m_protocols{protocols.begin(), protocols.end()} {
diff --git a/wpiutil/src/main/native/include/wpi/SpanExtras.h b/wpiutil/src/main/native/include/wpi/SpanExtras.h
new file mode 100644
index 0000000000..41e4014674
--- /dev/null
+++ b/wpiutil/src/main/native/include/wpi/SpanExtras.h
@@ -0,0 +1,27 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#pragma once
+
+#include <cassert>
+
+#include "wpi/span.h"
+
+namespace wpi {
+
+/// Drop the first \p N elements of the array.
+template <typename T>
+constexpr span<T> drop_front(span<T> in, typename span<T>::size_type n = 1) {
+  assert(in.size() >= n && "Dropping more elements than exist");
+  return in.subspan(n, in.size() - n);
+}
+
+/// Drop the last \p N elements of the array.
+template <typename T>
+constexpr span<T> drop_back(span<T> in, typename span<T>::size_type n = 1) {
+  assert(in.size() >= n && "Dropping more elements than exist");
+  return in.subspan(0, in.size() - n);
+}
+
+}  // namespace wpi
diff --git a/wpiutil/src/main/native/include/wpi/TCPConnector.h b/wpiutil/src/main/native/include/wpi/TCPConnector.h
index a05342ba39..63e8906ea5 100644
--- a/wpiutil/src/main/native/include/wpi/TCPConnector.h
+++ b/wpiutil/src/main/native/include/wpi/TCPConnector.h
@@ -27,8 +27,8 @@
 #include <memory>
 #include <utility>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/NetworkStream.h"
+#include "wpi/span.h"
 
 namespace wpi {
 
@@ -40,7 +40,7 @@ class TCPConnector {
                                                 Logger& logger,
                                                 int timeout = 0);
   static std::unique_ptr<NetworkStream> connect_parallel(
-      ArrayRef<std::pair<const char*, int>> servers, Logger& logger,
+      span<const std::pair<const char*, int>> servers, Logger& logger,
       int timeout = 0);
 };
 
diff --git a/wpiutil/src/main/native/include/wpi/UDPClient.h b/wpiutil/src/main/native/include/wpi/UDPClient.h
index ec06c8ce97..fd2e30bf30 100644
--- a/wpiutil/src/main/native/include/wpi/UDPClient.h
+++ b/wpiutil/src/main/native/include/wpi/UDPClient.h
@@ -8,9 +8,9 @@
 #include <string>
 #include <string_view>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/SmallVector.h"
 #include "wpi/mutex.h"
+#include "wpi/span.h"
 
 namespace wpi {
 
@@ -36,7 +36,7 @@ class UDPClient {
   int start(int port);
   void shutdown();
   // The passed in address MUST be a resolved IP address.
-  int send(ArrayRef<uint8_t> data, std::string_view server, int port);
+  int send(span<const uint8_t> data, std::string_view server, int port);
   int send(std::string_view data, std::string_view server, int port);
   int receive(uint8_t* data_received, int receive_len);
   int receive(uint8_t* data_received, int receive_len,
diff --git a/wpiutil/src/main/native/include/wpi/WebSocket.h b/wpiutil/src/main/native/include/wpi/WebSocket.h
index a86481908c..8b585347dc 100644
--- a/wpiutil/src/main/native/include/wpi/WebSocket.h
+++ b/wpiutil/src/main/native/include/wpi/WebSocket.h
@@ -14,9 +14,9 @@
 #include <string_view>
 #include <utility>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/Signal.h"
 #include "wpi/SmallVector.h"
+#include "wpi/span.h"
 #include "wpi/uv/Buffer.h"
 #include "wpi/uv/Error.h"
 #include "wpi/uv/Timer.h"
@@ -78,7 +78,7 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
     uv::Timer::Time handshakeTimeout;  // NOLINT
 
     /** Additional headers to include in handshake. */
-    ArrayRef<std::pair<std::string_view, std::string_view>> extraHeaders;
+    span<const std::pair<std::string_view, std::string_view>> extraHeaders;
   };
 
   /**
@@ -93,7 +93,7 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
    */
   static std::shared_ptr<WebSocket> CreateClient(
       uv::Stream& stream, std::string_view uri, std::string_view host,
-      ArrayRef<std::string_view> protocols = {},
+      span<const std::string_view> protocols = {},
       const ClientOptions& options = {});
 
   /**
@@ -110,8 +110,7 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
       uv::Stream& stream, std::string_view uri, std::string_view host,
       std::initializer_list<std::string_view> protocols,
       const ClientOptions& options = {}) {
-    return CreateClient(stream, uri, host,
-                        makeArrayRef(protocols.begin(), protocols.end()),
+    return CreateClient(stream, uri, host, {protocols.begin(), protocols.end()},
                         options);
   }
 
@@ -182,23 +181,41 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
    * @param data UTF-8 encoded data to send
    * @param callback Callback which is invoked when the write completes.
    */
-  void SendText(
-      ArrayRef<uv::Buffer> data,
-      std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback) {
+  void SendText(span<const uv::Buffer> data,
+                std::function<void(span<uv::Buffer>, uv::Error)> callback) {
     Send(kFlagFin | kOpText, data, callback);
   }
 
+  /**
+   * Send a text message.
+   * @param data UTF-8 encoded data to send
+   * @param callback Callback which is invoked when the write completes.
+   */
+  void SendText(std::initializer_list<uv::Buffer> data,
+                std::function<void(span<uv::Buffer>, uv::Error)> callback) {
+    SendText({data.begin(), data.end()}, callback);
+  }
+
   /**
    * Send a binary message.
    * @param data Data to send
    * @param callback Callback which is invoked when the write completes.
    */
-  void SendBinary(
-      ArrayRef<uv::Buffer> data,
-      std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback) {
+  void SendBinary(span<const uv::Buffer> data,
+                  std::function<void(span<uv::Buffer>, uv::Error)> callback) {
     Send(kFlagFin | kOpBinary, data, callback);
   }
 
+  /**
+   * Send a binary message.
+   * @param data Data to send
+   * @param callback Callback which is invoked when the write completes.
+   */
+  void SendBinary(std::initializer_list<uv::Buffer> data,
+                  std::function<void(span<uv::Buffer>, uv::Error)> callback) {
+    SendBinary({data.begin(), data.end()}, callback);
+  }
+
   /**
    * Send a text message fragment.  This must be followed by one or more
    * SendFragment() calls, where the last one has fin=True, to complete the
@@ -207,11 +224,24 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
    * @param callback Callback which is invoked when the write completes.
    */
   void SendTextFragment(
-      ArrayRef<uv::Buffer> data,
-      std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback) {
+      span<const uv::Buffer> data,
+      std::function<void(span<uv::Buffer>, uv::Error)> callback) {
     Send(kOpText, data, callback);
   }
 
+  /**
+   * Send a text message fragment.  This must be followed by one or more
+   * SendFragment() calls, where the last one has fin=True, to complete the
+   * message.
+   * @param data UTF-8 encoded data to send
+   * @param callback Callback which is invoked when the write completes.
+   */
+  void SendTextFragment(
+      std::initializer_list<uv::Buffer> data,
+      std::function<void(span<uv::Buffer>, uv::Error)> callback) {
+    SendTextFragment({data.begin(), data.end()}, callback);
+  }
+
   /**
    * Send a text message fragment.  This must be followed by one or more
    * SendFragment() calls, where the last one has fin=True, to complete the
@@ -220,11 +250,24 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
    * @param callback Callback which is invoked when the write completes.
    */
   void SendBinaryFragment(
-      ArrayRef<uv::Buffer> data,
-      std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback) {
+      span<const uv::Buffer> data,
+      std::function<void(span<uv::Buffer>, uv::Error)> callback) {
     Send(kOpBinary, data, callback);
   }
 
+  /**
+   * Send a text message fragment.  This must be followed by one or more
+   * SendFragment() calls, where the last one has fin=True, to complete the
+   * message.
+   * @param data Data to send
+   * @param callback Callback which is invoked when the write completes.
+   */
+  void SendBinaryFragment(
+      std::initializer_list<uv::Buffer> data,
+      std::function<void(span<uv::Buffer>, uv::Error)> callback) {
+    SendBinaryFragment({data.begin(), data.end()}, callback);
+  }
+
   /**
    * Send a continuation frame.  This is used to send additional parts of a
    * message started with SendTextFragment() or SendBinaryFragment().
@@ -232,19 +275,30 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
    * @param fin Set to true if this is the final fragment of the message
    * @param callback Callback which is invoked when the write completes.
    */
-  void SendFragment(
-      ArrayRef<uv::Buffer> data, bool fin,
-      std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback) {
+  void SendFragment(span<const uv::Buffer> data, bool fin,
+                    std::function<void(span<uv::Buffer>, uv::Error)> callback) {
     Send(kOpCont | (fin ? kFlagFin : 0), data, callback);
   }
 
+  /**
+   * Send a continuation frame.  This is used to send additional parts of a
+   * message started with SendTextFragment() or SendBinaryFragment().
+   * @param data Data to send
+   * @param fin Set to true if this is the final fragment of the message
+   * @param callback Callback which is invoked when the write completes.
+   */
+  void SendFragment(std::initializer_list<uv::Buffer> data, bool fin,
+                    std::function<void(span<uv::Buffer>, uv::Error)> callback) {
+    SendFragment({data.begin(), data.end()}, fin, callback);
+  }
+
   /**
    * Send a ping frame with no data.
    * @param callback Optional callback which is invoked when the ping frame
    *                 write completes.
    */
   void SendPing(std::function<void(uv::Error)> callback = nullptr) {
-    SendPing(ArrayRef<uv::Buffer>{}, [callback](auto bufs, uv::Error err) {
+    SendPing({}, [callback](auto bufs, uv::Error err) {
       if (callback) {
         callback(err);
       }
@@ -257,19 +311,29 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
    * @param callback Callback which is invoked when the ping frame
    *                 write completes.
    */
-  void SendPing(
-      ArrayRef<uv::Buffer> data,
-      std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback) {
+  void SendPing(span<const uv::Buffer> data,
+                std::function<void(span<uv::Buffer>, uv::Error)> callback) {
     Send(kFlagFin | kOpPing, data, callback);
   }
 
+  /**
+   * Send a ping frame.
+   * @param data Data to send in the ping frame
+   * @param callback Callback which is invoked when the ping frame
+   *                 write completes.
+   */
+  void SendPing(std::initializer_list<uv::Buffer> data,
+                std::function<void(span<uv::Buffer>, uv::Error)> callback) {
+    SendPing({data.begin(), data.end()}, callback);
+  }
+
   /**
    * Send a pong frame with no data.
    * @param callback Optional callback which is invoked when the pong frame
    *                 write completes.
    */
   void SendPong(std::function<void(uv::Error)> callback = nullptr) {
-    SendPong(ArrayRef<uv::Buffer>{}, [callback](auto bufs, uv::Error err) {
+    SendPong({}, [callback](auto bufs, uv::Error err) {
       if (callback) {
         callback(err);
       }
@@ -282,12 +346,22 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
    * @param callback Callback which is invoked when the pong frame
    *                 write completes.
    */
-  void SendPong(
-      ArrayRef<uv::Buffer> data,
-      std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback) {
+  void SendPong(span<const uv::Buffer> data,
+                std::function<void(span<uv::Buffer>, uv::Error)> callback) {
     Send(kFlagFin | kOpPong, data, callback);
   }
 
+  /**
+   * Send a pong frame.
+   * @param data Data to send in the pong frame
+   * @param callback Callback which is invoked when the pong frame
+   *                 write completes.
+   */
+  void SendPong(std::initializer_list<uv::Buffer> data,
+                std::function<void(span<uv::Buffer>, uv::Error)> callback) {
+    SendPong({data.begin(), data.end()}, callback);
+  }
+
   /**
    * Fail the connection.
    */
@@ -339,17 +413,17 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
    * The first parameter is the data, the second parameter is true if the
    * data is the last fragment of the message.
    */
-  sig::Signal<ArrayRef<uint8_t>, bool> binary;
+  sig::Signal<span<const uint8_t>, bool> binary;
 
   /**
    * Ping event.  Emitted when a ping message is received.
    */
-  sig::Signal<ArrayRef<uint8_t>> ping;
+  sig::Signal<span<const uint8_t>> ping;
 
   /**
    * Pong event.  Emitted when a pong message is received.
    */
-  sig::Signal<ArrayRef<uint8_t>> pong;
+  sig::Signal<span<const uint8_t>> pong;
 
  private:
   // user data
@@ -382,7 +456,7 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
   std::unique_ptr<ClientHandshakeData> m_clientHandshake;
 
   void StartClient(std::string_view uri, std::string_view host,
-                   ArrayRef<std::string_view> protocols,
+                   span<const std::string_view> protocols,
                    const ClientOptions& options);
   void StartServer(std::string_view key, std::string_view version,
                    std::string_view protocol);
@@ -390,9 +464,8 @@ class WebSocket : public std::enable_shared_from_this<WebSocket> {
   void SetClosed(uint16_t code, std::string_view reason, bool failed = false);
   void Shutdown();
   void HandleIncoming(uv::Buffer& buf, size_t size);
-  void Send(
-      uint8_t opcode, ArrayRef<uv::Buffer> data,
-      std::function<void(MutableArrayRef<uv::Buffer>, uv::Error)> callback);
+  void Send(uint8_t opcode, span<const uv::Buffer> data,
+            std::function<void(span<uv::Buffer>, uv::Error)> callback);
 };
 
 }  // namespace wpi
diff --git a/wpiutil/src/main/native/include/wpi/WebSocketServer.h b/wpiutil/src/main/native/include/wpi/WebSocketServer.h
index afae8f03ae..1f76d16b91 100644
--- a/wpiutil/src/main/native/include/wpi/WebSocketServer.h
+++ b/wpiutil/src/main/native/include/wpi/WebSocketServer.h
@@ -12,12 +12,12 @@
 #include <string_view>
 #include <utility>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/HttpParser.h"
 #include "wpi/Signal.h"
 #include "wpi/SmallString.h"
 #include "wpi/SmallVector.h"
 #include "wpi/WebSocket.h"
+#include "wpi/span.h"
 
 namespace wpi {
 
@@ -53,7 +53,7 @@ class WebSocketServerHelper {
    *         is empty.
    */
   std::pair<bool, std::string_view> MatchProtocol(
-      ArrayRef<std::string_view> protocols);
+      span<const std::string_view> protocols);
 
   /**
    * Try to find a match to the list of sub-protocols provided by the client.
@@ -66,7 +66,7 @@ class WebSocketServerHelper {
    */
   std::pair<bool, std::string_view> MatchProtocol(
       std::initializer_list<std::string_view> protocols) {
-    return MatchProtocol(makeArrayRef(protocols.begin(), protocols.end()));
+    return MatchProtocol({protocols.begin(), protocols.end()});
   }
 
   /**
@@ -122,7 +122,7 @@ class WebSocketServer : public std::enable_shared_from_this<WebSocketServer> {
   /**
    * Private constructor.
    */
-  WebSocketServer(uv::Stream& stream, ArrayRef<std::string_view> protocols,
+  WebSocketServer(uv::Stream& stream, span<const std::string_view> protocols,
                   ServerOptions options, const private_init&);
 
   /**
@@ -135,7 +135,7 @@ class WebSocketServer : public std::enable_shared_from_this<WebSocketServer> {
    * @param options Handshake options
    */
   static std::shared_ptr<WebSocketServer> Create(
-      uv::Stream& stream, ArrayRef<std::string_view> protocols = {},
+      uv::Stream& stream, span<const std::string_view> protocols = {},
       const ServerOptions& options = {});
 
   /**
@@ -150,8 +150,7 @@ class WebSocketServer : public std::enable_shared_from_this<WebSocketServer> {
   static std::shared_ptr<WebSocketServer> Create(
       uv::Stream& stream, std::initializer_list<std::string_view> protocols,
       const ServerOptions& options = {}) {
-    return Create(stream, makeArrayRef(protocols.begin(), protocols.end()),
-                  options);
+    return Create(stream, {protocols.begin(), protocols.end()}, options);
   }
 
   /**
diff --git a/wpiutil/src/main/native/include/wpi/jni_util.h b/wpiutil/src/main/native/include/wpi/jni_util.h
index 129a5b7200..557cfa2652 100644
--- a/wpiutil/src/main/native/include/wpi/jni_util.h
+++ b/wpiutil/src/main/native/include/wpi/jni_util.h
@@ -14,7 +14,6 @@
 #include <utility>
 #include <vector>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/ConvertUTF.h"
 #include "wpi/SafeThread.h"
 #include "wpi/SmallString.h"
@@ -23,6 +22,7 @@
 #include "wpi/deprecated.h"
 #include "wpi/mutex.h"
 #include "wpi/raw_ostream.h"
+#include "wpi/span.h"
 
 /** Java Native Interface (JNI) utility functions */
 namespace wpi::java {
@@ -137,7 +137,7 @@ class JStringRef {
       jsize size = env->GetStringLength(str);
       const jchar* chars = env->GetStringCritical(str, nullptr);
       if (chars) {
-        convertUTF16ToUTF8String(makeArrayRef(chars, size), m_str);
+        convertUTF16ToUTF8String(wpi::span<const jchar>(chars, size), m_str);
         env->ReleaseStringCritical(str, chars);
       }
     } else {
@@ -185,13 +185,13 @@ class JArrayRefBase : public JArrayRefInner<JArrayRefBase<T>, T> {
  public:
   explicit operator bool() const { return this->m_elements != nullptr; }
 
-  operator ArrayRef<T>() const { return array(); }  // NOLINT
+  operator span<const T>() const { return array(); }  // NOLINT
 
-  ArrayRef<T> array() const {
+  span<const T> array() const {
     if (!this->m_elements) {
       return {};
     }
-    return ArrayRef<T>{this->m_elements, this->m_size};
+    return {this->m_elements, this->m_size};
   }
 
   JArrayRefBase(const JArrayRefBase&) = delete;
@@ -342,7 +342,7 @@ namespace detail {
 template <typename T,
           bool = (std::is_integral<T>::value && sizeof(jint) == sizeof(T))>
 struct ConvertIntArray {
-  static jintArray ToJava(JNIEnv* env, ArrayRef<T> arr) {
+  static jintArray ToJava(JNIEnv* env, span<const T> arr) {
     jintArray jarr = env->NewIntArray(arr.size());
     if (!jarr) {
       return nullptr;
@@ -363,7 +363,7 @@ struct ConvertIntArray {
 // Fast path (use SetIntArrayRegion)
 template <typename T>
 struct ConvertIntArray<T, true> {
-  static jintArray ToJava(JNIEnv* env, ArrayRef<T> arr) {
+  static jintArray ToJava(JNIEnv* env, span<const T> arr) {
     jintArray jarr = env->NewIntArray(arr.size());
     if (!jarr) {
       return nullptr;
@@ -376,9 +376,14 @@ struct ConvertIntArray<T, true> {
 
 }  // namespace detail
 
-// Convert an ArrayRef to a jintArray.
+// Convert an span to a jintArray.
 template <typename T>
-inline jintArray MakeJIntArray(JNIEnv* env, ArrayRef<T> arr) {
+inline jintArray MakeJIntArray(JNIEnv* env, span<const T> arr) {
+  return detail::ConvertIntArray<T>::ToJava(env, arr);
+}
+
+template <typename T>
+inline jintArray MakeJIntArray(JNIEnv* env, span<T> arr) {
   return detail::ConvertIntArray<T>::ToJava(env, arr);
 }
 
@@ -408,7 +413,7 @@ inline jbyteArray MakeJByteArray(JNIEnv* env, std::string_view str) {
 }
 
 // Convert an array of integers into a jbooleanArray.
-inline jbooleanArray MakeJBooleanArray(JNIEnv* env, ArrayRef<int> arr) {
+inline jbooleanArray MakeJBooleanArray(JNIEnv* env, span<const int> arr) {
   jbooleanArray jarr = env->NewBooleanArray(arr.size());
   if (!jarr) {
     return nullptr;
@@ -426,7 +431,7 @@ inline jbooleanArray MakeJBooleanArray(JNIEnv* env, ArrayRef<int> arr) {
 }
 
 // Convert an array of booleans into a jbooleanArray.
-inline jbooleanArray MakeJBooleanArray(JNIEnv* env, ArrayRef<bool> arr) {
+inline jbooleanArray MakeJBooleanArray(JNIEnv* env, span<const bool> arr) {
   jbooleanArray jarr = env->NewBooleanArray(arr.size());
   if (!jarr) {
     return nullptr;
@@ -445,14 +450,14 @@ inline jbooleanArray MakeJBooleanArray(JNIEnv* env, ArrayRef<bool> arr) {
 
 // Other MakeJ*Array conversions.
 
-#define WPI_JNI_MAKEJARRAY(T, F)                                  \
-  inline T##Array MakeJ##F##Array(JNIEnv* env, ArrayRef<T> arr) { \
-    T##Array jarr = env->New##F##Array(arr.size());               \
-    if (!jarr) {                                                  \
-      return nullptr;                                             \
-    }                                                             \
-    env->Set##F##ArrayRegion(jarr, 0, arr.size(), arr.data());    \
-    return jarr;                                                  \
+#define WPI_JNI_MAKEJARRAY(T, F)                                    \
+  inline T##Array MakeJ##F##Array(JNIEnv* env, span<const T> arr) { \
+    T##Array jarr = env->New##F##Array(arr.size());                 \
+    if (!jarr) {                                                    \
+      return nullptr;                                               \
+    }                                                               \
+    env->Set##F##ArrayRegion(jarr, 0, arr.size(), arr.data());      \
+    return jarr;                                                    \
   }
 
 WPI_JNI_MAKEJARRAY(jboolean, Boolean)
@@ -465,7 +470,7 @@ WPI_JNI_MAKEJARRAY(jdouble, Double)
 #undef WPI_JNI_MAKEJARRAY
 
 // Convert an array of std::string into a jarray of jstring.
-inline jobjectArray MakeJStringArray(JNIEnv* env, ArrayRef<std::string> arr) {
+inline jobjectArray MakeJStringArray(JNIEnv* env, span<const std::string> arr) {
   static JClass stringCls{env, "java/lang/String"};
   if (!stringCls) {
     return nullptr;
diff --git a/wpiutil/src/main/native/include/wpi/json.h b/wpiutil/src/main/native/include/wpi/json.h
index 873e2e5712..67578a562a 100644
--- a/wpiutil/src/main/native/include/wpi/json.h
+++ b/wpiutil/src/main/native/include/wpi/json.h
@@ -60,8 +60,8 @@ SOFTWARE.
 #include <utility>
 #include <vector> // vector
 
-#include "wpi/ArrayRef.h"
 #include "wpi/StringMap.h"
+#include "wpi/span.h"
 
 namespace wpi
 {
@@ -1126,7 +1126,7 @@ struct external_constructor<value_t::array>
     }
 
     template<typename BasicJsonType, typename T>
-    static void construct(BasicJsonType& j, ArrayRef<T> arr)
+    static void construct(BasicJsonType& j, span<T> arr)
     {
         using std::begin;
         using std::end;
@@ -7014,7 +7014,7 @@ class json
                             const parser_callback_t cb = nullptr,
                             const bool allow_exceptions = true);
 
-    static json parse(ArrayRef<uint8_t> arr,
+    static json parse(span<const uint8_t> arr,
                             const parser_callback_t cb = nullptr,
                             const bool allow_exceptions = true);
 
@@ -7027,7 +7027,7 @@ class json
 
     static bool accept(std::string_view s);
 
-    static bool accept(ArrayRef<uint8_t> arr);
+    static bool accept(span<const uint8_t> arr);
 
     static bool accept(raw_istream& i);
 
@@ -7205,8 +7205,8 @@ class json
     @since version 2.0.9
     */
     static std::vector<uint8_t> to_cbor(const json& j);
-    static ArrayRef<uint8_t> to_cbor(const json& j, std::vector<uint8_t>& buf);
-    static ArrayRef<uint8_t> to_cbor(const json& j, SmallVectorImpl<uint8_t>& buf);
+    static span<uint8_t> to_cbor(const json& j, std::vector<uint8_t>& buf);
+    static span<uint8_t> to_cbor(const json& j, SmallVectorImpl<uint8_t>& buf);
     static void to_cbor(raw_ostream& os, const json& j);
 
     /*!
@@ -7290,8 +7290,8 @@ class json
     @since version 2.0.9
     */
     static std::vector<uint8_t> to_msgpack(const json& j);
-    static ArrayRef<uint8_t> to_msgpack(const json& j, std::vector<uint8_t>& buf);
-    static ArrayRef<uint8_t> to_msgpack(const json& j, SmallVectorImpl<uint8_t>& buf);
+    static span<uint8_t> to_msgpack(const json& j, std::vector<uint8_t>& buf);
+    static span<uint8_t> to_msgpack(const json& j, SmallVectorImpl<uint8_t>& buf);
     static void to_msgpack(raw_ostream& os, const json& j);
 
     /*!
@@ -7377,10 +7377,10 @@ class json
     static std::vector<uint8_t> to_ubjson(const json& j,
                                           const bool use_size = false,
                                           const bool use_type = false);
-    static ArrayRef<uint8_t> to_ubjson(const json& j, std::vector<uint8_t>& buf,
-                                       const bool use_size = false, const bool use_type = false);
-    static ArrayRef<uint8_t> to_ubjson(const json& j, SmallVectorImpl<uint8_t>& buf,
-                                       const bool use_size = false, const bool use_type = false);
+    static span<uint8_t> to_ubjson(const json& j, std::vector<uint8_t>& buf,
+                                   const bool use_size = false, const bool use_type = false);
+    static span<uint8_t> to_ubjson(const json& j, SmallVectorImpl<uint8_t>& buf,
+                                   const bool use_size = false, const bool use_type = false);
     static void to_ubjson(raw_ostream& os, const json& j,
                           const bool use_size = false, const bool use_type = false);
 
@@ -7483,7 +7483,7 @@ class json
     /*!
     @copydoc from_cbor(raw_istream&, const bool)
     */
-    static json from_cbor(ArrayRef<uint8_t> arr, const bool strict = true);
+    static json from_cbor(span<const uint8_t> arr, const bool strict = true);
 
     /*!
     @brief create a JSON value from an input in MessagePack format
@@ -7564,7 +7564,7 @@ class json
     /*!
     @copydoc from_msgpack(raw_istream, const bool)
     */
-    static json from_msgpack(ArrayRef<uint8_t> arr, const bool strict = true);
+    static json from_msgpack(span<const uint8_t> arr, const bool strict = true);
 
     /*!
     @brief create a JSON value from an input in UBJSON format
@@ -7622,7 +7622,7 @@ class json
     static json from_ubjson(raw_istream& is,
                                   const bool strict = true);
 
-    static json from_ubjson(ArrayRef<uint8_t> arr, const bool strict = true);
+    static json from_ubjson(span<const uint8_t> arr, const bool strict = true);
 
     /// @}
 
diff --git a/wpiutil/src/main/native/include/wpi/raw_istream.h b/wpiutil/src/main/native/include/wpi/raw_istream.h
index aab3866ad9..2371fc666c 100644
--- a/wpiutil/src/main/native/include/wpi/raw_istream.h
+++ b/wpiutil/src/main/native/include/wpi/raw_istream.h
@@ -14,8 +14,8 @@
 #include <system_error>
 #include <vector>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/SmallVector.h"
+#include "wpi/span.h"
 
 namespace wpi {
 
@@ -133,9 +133,9 @@ class raw_mem_istream : public raw_istream {
   // not const as we don't want to allow temporaries
   explicit raw_mem_istream(std::string& str)
       : raw_mem_istream(str.data(), str.size()) {}
-  explicit raw_mem_istream(ArrayRef<char> mem)
+  explicit raw_mem_istream(span<const char> mem)
       : raw_mem_istream(mem.data(), mem.size()) {}
-  explicit raw_mem_istream(ArrayRef<uint8_t> mem)
+  explicit raw_mem_istream(span<const uint8_t> mem)
       : raw_mem_istream(reinterpret_cast<const char*>(mem.data()), mem.size()) {
   }
   explicit raw_mem_istream(const char* str)
diff --git a/wpiutil/src/main/native/include/wpi/raw_ostream.h b/wpiutil/src/main/native/include/wpi/raw_ostream.h
index 7e4a0c1c14..84ec925435 100644
--- a/wpiutil/src/main/native/include/wpi/raw_ostream.h
+++ b/wpiutil/src/main/native/include/wpi/raw_ostream.h
@@ -14,8 +14,8 @@
 #ifndef WPIUTIL_WPI_RAW_OSTREAM_H
 #define WPIUTIL_WPI_RAW_OSTREAM_H
 
-#include "wpi/ArrayRef.h"
 #include "wpi/SmallVector.h"
+#include "wpi/span.h"
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
@@ -159,7 +159,7 @@ public:
     return *this;
   }
 
-  raw_ostream &operator<<(ArrayRef<uint8_t> Arr) {
+  raw_ostream &operator<<(span<const uint8_t> Arr) {
     // Inline fast path, particularly for arrays with a known length.
     size_t Size = Arr.size();
 
@@ -573,8 +573,9 @@ public:
 
   void flush() = delete;
 
-  /// Return an ArrayRef for the vector contents.
-  ArrayRef<uint8_t> array() { return ArrayRef<uint8_t>(OS.data(), OS.size()); }
+  /// Return an span for the vector contents.
+  span<uint8_t> array() { return {OS.data(), OS.size()}; }
+  span<const uint8_t> array() const { return {OS.data(), OS.size()}; }
 };
 
 /// A raw_ostream that writes to a vector.  This is a
@@ -606,8 +607,9 @@ public:
 
   void flush() = delete;
 
-  /// Return a ArrayRef for the vector contents.
-  ArrayRef<uint8_t> array() { return ArrayRef<uint8_t>(OS.data(), OS.size()); }
+  /// Return a span for the vector contents.
+  span<uint8_t> array() { return {OS.data(), OS.size()}; }
+  span<const uint8_t> array() const { return {OS.data(), OS.size()}; }
 };
 
 
diff --git a/wpiutil/src/main/native/include/wpi/raw_uv_ostream.h b/wpiutil/src/main/native/include/wpi/raw_uv_ostream.h
index ba6ad51e1d..12580ac89d 100644
--- a/wpiutil/src/main/native/include/wpi/raw_uv_ostream.h
+++ b/wpiutil/src/main/native/include/wpi/raw_uv_ostream.h
@@ -5,11 +5,12 @@
 #ifndef WPIUTIL_WPI_RAW_UV_OSTREAM_H_
 #define WPIUTIL_WPI_RAW_UV_OSTREAM_H_
 
+#include <functional>
 #include <utility>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/SmallVector.h"
 #include "wpi/raw_ostream.h"
+#include "wpi/span.h"
 #include "wpi/uv/Buffer.h"
 
 namespace wpi {
@@ -47,9 +48,9 @@ class raw_uv_ostream : public raw_ostream {
   ~raw_uv_ostream() override = default;
 
   /**
-   * Returns an ArrayRef to the buffers.
+   * Returns an span to the buffers.
    */
-  ArrayRef<uv::Buffer> bufs() { return m_bufs; }
+  span<uv::Buffer> bufs() { return m_bufs; }
 
   void flush() = delete;
 
diff --git a/wpiutil/src/main/native/include/wpi/uv/Buffer.h b/wpiutil/src/main/native/include/wpi/uv/Buffer.h
index cd47b6c8e9..51268414e9 100644
--- a/wpiutil/src/main/native/include/wpi/uv/Buffer.h
+++ b/wpiutil/src/main/native/include/wpi/uv/Buffer.h
@@ -12,8 +12,8 @@
 #include <string_view>
 #include <utility>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/SmallVector.h"
+#include "wpi/span.h"
 
 namespace wpi::uv {
 
@@ -32,7 +32,7 @@ class Buffer : public uv_buf_t {
   }
   /*implicit*/ Buffer(std::string_view str)  // NOLINT
       : Buffer{str.data(), str.size()} {}
-  /*implicit*/ Buffer(ArrayRef<uint8_t> arr)  // NOLINT
+  /*implicit*/ Buffer(span<const uint8_t> arr)  // NOLINT
       : Buffer{reinterpret_cast<const char*>(arr.data()), arr.size()} {}
   Buffer(char* base_, size_t len_) {
     base = base_;
@@ -43,11 +43,11 @@ class Buffer : public uv_buf_t {
     len = static_cast<decltype(len)>(len_);
   }
 
-  ArrayRef<char> data() const { return ArrayRef<char>{base, len}; }
-  MutableArrayRef<char> data() { return MutableArrayRef<char>{base, len}; }
+  span<const char> data() const { return {base, len}; }
+  span<char> data() { return {base, len}; }
 
-  operator ArrayRef<char>() const { return data(); }   // NOLINT
-  operator MutableArrayRef<char>() { return data(); }  // NOLINT
+  operator span<const char>() const { return data(); }  // NOLINT
+  operator span<char>() { return data(); }              // NOLINT
 
   static Buffer Allocate(size_t size) { return Buffer{new char[size], size}; }
 
@@ -57,7 +57,7 @@ class Buffer : public uv_buf_t {
     return buf;
   }
 
-  static Buffer Dup(ArrayRef<uint8_t> in) {
+  static Buffer Dup(span<const uint8_t> in) {
     Buffer buf = Allocate(in.size());
     std::memcpy(buf.base, in.begin(), in.size());
     return buf;
@@ -131,7 +131,7 @@ class SimpleBufferPool {
    * This is NOT safe to use with arbitrary buffers unless they were
    * allocated with the same size as the buffer pool allocation size.
    */
-  void Release(MutableArrayRef<Buffer> bufs) {
+  void Release(span<Buffer> bufs) {
     for (auto& buf : bufs) {
       m_pool.emplace_back(buf.Move());
     }
diff --git a/wpiutil/src/main/native/include/wpi/uv/Process.h b/wpiutil/src/main/native/include/wpi/uv/Process.h
index 8e5ebc80d0..fc2315eebd 100644
--- a/wpiutil/src/main/native/include/wpi/uv/Process.h
+++ b/wpiutil/src/main/native/include/wpi/uv/Process.h
@@ -12,9 +12,9 @@
 #include <string>
 #include <string_view>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/Signal.h"
 #include "wpi/SmallVector.h"
+#include "wpi/span.h"
 #include "wpi/uv/Handle.h"
 
 namespace wpi::uv {
@@ -232,12 +232,12 @@ class Process final : public HandleImpl<Process, uv_process_t> {
    * @param options Process options
    */
   static std::shared_ptr<Process> SpawnArray(Loop& loop, std::string_view file,
-                                             ArrayRef<Option> options);
+                                             span<const Option> options);
 
   static std::shared_ptr<Process> SpawnArray(
       Loop& loop, std::string_view file,
       std::initializer_list<Option> options) {
-    return SpawnArray(loop, file, makeArrayRef(options.begin(), options.end()));
+    return SpawnArray(loop, file, {options.begin(), options.end()});
   }
 
   template <typename... Args>
@@ -261,7 +261,7 @@ class Process final : public HandleImpl<Process, uv_process_t> {
    */
   static std::shared_ptr<Process> SpawnArray(const std::shared_ptr<Loop>& loop,
                                              std::string_view file,
-                                             ArrayRef<Option> options) {
+                                             span<const Option> options) {
     return SpawnArray(*loop, file, options);
   }
 
diff --git a/wpiutil/src/main/native/include/wpi/uv/Stream.h b/wpiutil/src/main/native/include/wpi/uv/Stream.h
index 1b90a992a3..31128f2607 100644
--- a/wpiutil/src/main/native/include/wpi/uv/Stream.h
+++ b/wpiutil/src/main/native/include/wpi/uv/Stream.h
@@ -12,8 +12,8 @@
 #include <initializer_list>
 #include <memory>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/Signal.h"
+#include "wpi/span.h"
 #include "wpi/uv/Buffer.h"
 #include "wpi/uv/Handle.h"
 #include "wpi/uv/Request.h"
@@ -126,7 +126,7 @@ class Stream : public Handle {
    * @param bufs The buffers to be written to the stream.
    * @param req write request
    */
-  void Write(ArrayRef<Buffer> bufs, const std::shared_ptr<WriteReq>& req);
+  void Write(span<const Buffer> bufs, const std::shared_ptr<WriteReq>& req);
 
   /**
    * Write data to the stream.
@@ -146,7 +146,7 @@ class Stream : public Handle {
    */
   void Write(std::initializer_list<Buffer> bufs,
              const std::shared_ptr<WriteReq>& req) {
-    Write(makeArrayRef(bufs.begin(), bufs.end()), req);
+    Write({bufs.begin(), bufs.end()}, req);
   }
 
   /**
@@ -162,8 +162,8 @@ class Stream : public Handle {
    * @param bufs The buffers to be written to the stream.
    * @param callback Callback function to call when the write completes
    */
-  void Write(ArrayRef<Buffer> bufs,
-             std::function<void(MutableArrayRef<Buffer>, Error)> callback);
+  void Write(span<const Buffer> bufs,
+             std::function<void(span<Buffer>, Error)> callback);
 
   /**
    * Write data to the stream.
@@ -179,8 +179,8 @@ class Stream : public Handle {
    * @param callback Callback function to call when the write completes
    */
   void Write(std::initializer_list<Buffer> bufs,
-             std::function<void(MutableArrayRef<Buffer>, Error)> callback) {
-    Write(makeArrayRef(bufs.begin(), bufs.end()), callback);
+             std::function<void(span<Buffer>, Error)> callback) {
+    Write({bufs.begin(), bufs.end()}, callback);
   }
 
   /**
@@ -193,7 +193,7 @@ class Stream : public Handle {
    * @param bufs The buffers to be written to the stream.
    * @return Number of bytes written.
    */
-  int TryWrite(ArrayRef<Buffer> bufs);
+  int TryWrite(span<const Buffer> bufs);
 
   /**
    * Queue a write request if it can be completed immediately.
@@ -206,7 +206,7 @@ class Stream : public Handle {
    * @return Number of bytes written.
    */
   int TryWrite(std::initializer_list<Buffer> bufs) {
-    return TryWrite(makeArrayRef(bufs.begin(), bufs.end()));
+    return TryWrite({bufs.begin(), bufs.end()});
   }
 
   /**
diff --git a/wpiutil/src/main/native/include/wpi/uv/Udp.h b/wpiutil/src/main/native/include/wpi/uv/Udp.h
index f4199bc8dd..083af1af9c 100644
--- a/wpiutil/src/main/native/include/wpi/uv/Udp.h
+++ b/wpiutil/src/main/native/include/wpi/uv/Udp.h
@@ -11,8 +11,8 @@
 #include <memory>
 #include <string_view>
 
-#include "wpi/ArrayRef.h"
 #include "wpi/Signal.h"
+#include "wpi/span.h"
 #include "wpi/uv/Handle.h"
 #include "wpi/uv/Request.h"
 
@@ -230,15 +230,15 @@ class Udp final : public HandleImpl<Udp, uv_udp_t> {
    * @param bufs The buffers to be written to the stream.
    * @param req write request
    */
-  void Send(const sockaddr& addr, ArrayRef<Buffer> bufs,
+  void Send(const sockaddr& addr, span<const Buffer> bufs,
             const std::shared_ptr<UdpSendReq>& req);
 
-  void Send(const sockaddr_in& addr, ArrayRef<Buffer> bufs,
+  void Send(const sockaddr_in& addr, span<const Buffer> bufs,
             const std::shared_ptr<UdpSendReq>& req) {
     Send(reinterpret_cast<const sockaddr&>(addr), bufs, req);
   }
 
-  void Send(const sockaddr_in6& addr, ArrayRef<Buffer> bufs,
+  void Send(const sockaddr_in6& addr, span<const Buffer> bufs,
             const std::shared_ptr<UdpSendReq>& req) {
     Send(reinterpret_cast<const sockaddr&>(addr), bufs, req);
   }
@@ -250,7 +250,7 @@ class Udp final : public HandleImpl<Udp, uv_udp_t> {
    * @param bufs The buffers to be written to the stream.
    * @param req write request
    */
-  void Send(ArrayRef<Buffer> bufs, const std::shared_ptr<UdpSendReq>& req);
+  void Send(span<const Buffer> bufs, const std::shared_ptr<UdpSendReq>& req);
 
   /**
    * Send data over the UDP socket.  If the socket has not previously been bound
@@ -269,16 +269,16 @@ class Udp final : public HandleImpl<Udp, uv_udp_t> {
    * @param bufs The buffers to be sent.
    * @param callback Callback function to call when the data has been sent.
    */
-  void Send(const sockaddr& addr, ArrayRef<Buffer> bufs,
-            std::function<void(MutableArrayRef<Buffer>, Error)> callback);
+  void Send(const sockaddr& addr, span<const Buffer> bufs,
+            std::function<void(span<Buffer>, Error)> callback);
 
-  void Send(const sockaddr_in& addr, ArrayRef<Buffer> bufs,
-            std::function<void(MutableArrayRef<Buffer>, Error)> callback) {
+  void Send(const sockaddr_in& addr, span<const Buffer> bufs,
+            std::function<void(span<Buffer>, Error)> callback) {
     Send(reinterpret_cast<const sockaddr&>(addr), bufs, callback);
   }
 
-  void Send(const sockaddr_in6& addr, ArrayRef<Buffer> bufs,
-            std::function<void(MutableArrayRef<Buffer>, Error)> callback) {
+  void Send(const sockaddr_in6& addr, span<const Buffer> bufs,
+            std::function<void(span<Buffer>, Error)> callback) {
     Send(reinterpret_cast<const sockaddr&>(addr), bufs, callback);
   }
 
@@ -289,8 +289,8 @@ class Udp final : public HandleImpl<Udp, uv_udp_t> {
    * @param bufs The buffers to be written to the stream.
    * @param callback Callback function to call when the data has been sent.
    */
-  void Send(ArrayRef<Buffer> bufs,
-            std::function<void(MutableArrayRef<Buffer>, Error)> callback);
+  void Send(span<const Buffer> bufs,
+            std::function<void(span<Buffer>, Error)> callback);
 
   /**
    * Same as Send(), but won't queue a send request if it can't be completed
@@ -301,7 +301,7 @@ class Udp final : public HandleImpl<Udp, uv_udp_t> {
    * @param bufs The buffers to be send.
    * @return Number of bytes sent.
    */
-  int TrySend(const sockaddr& addr, ArrayRef<Buffer> bufs) {
+  int TrySend(const sockaddr& addr, span<const Buffer> bufs) {
     int val = uv_udp_try_send(GetRaw(), bufs.data(),
                               static_cast<unsigned>(bufs.size()), &addr);
     if (val < 0) {
@@ -311,11 +311,11 @@ class Udp final : public HandleImpl<Udp, uv_udp_t> {
     return val;
   }
 
-  int TrySend(const sockaddr_in& addr, ArrayRef<Buffer> bufs) {
+  int TrySend(const sockaddr_in& addr, span<const Buffer> bufs) {
     return TrySend(reinterpret_cast<const sockaddr&>(addr), bufs);
   }
 
-  int TrySend(const sockaddr_in6& addr, ArrayRef<Buffer> bufs) {
+  int TrySend(const sockaddr_in6& addr, span<const Buffer> bufs) {
     return TrySend(reinterpret_cast<const sockaddr&>(addr), bufs);
   }
 
@@ -326,7 +326,7 @@ class Udp final : public HandleImpl<Udp, uv_udp_t> {
    * @param bufs The buffers to be written to the stream.
    * @return Number of bytes sent.
    */
-  int TrySend(ArrayRef<Buffer> bufs) {
+  int TrySend(span<const Buffer> bufs) {
     int val = uv_udp_try_send(GetRaw(), bufs.data(),
                               static_cast<unsigned>(bufs.size()), nullptr);
     if (val < 0) {
diff --git a/wpiutil/src/netconsoleServer/native/cpp/main.cpp b/wpiutil/src/netconsoleServer/native/cpp/main.cpp
index fdd3be32a8..c43a670338 100644
--- a/wpiutil/src/netconsoleServer/native/cpp/main.cpp
+++ b/wpiutil/src/netconsoleServer/native/cpp/main.cpp
@@ -57,7 +57,7 @@ static bool NewlineBuffer(std::string& rem, uv::Buffer& buf, size_t len,
                               static_cast<uint8_t>(ts & 0xff),
                               static_cast<uint8_t>((tcpSeq >> 8) & 0xff),
                               static_cast<uint8_t>(tcpSeq & 0xff)};
-    out << wpi::ArrayRef<uint8_t>(header);
+    out << wpi::span<const uint8_t>(header);
   }
   out << rem << toCopy;
 
@@ -123,7 +123,7 @@ static void CopyStream(uv::Stream& in, std::shared_ptr<uv::Stream> out) {
   in.data.connect([out](uv::Buffer& buf, size_t len) {
     uv::Buffer buf2 = buf.Dup();
     buf2.len = len;
-    out->Write(buf2, [](auto bufs, uv::Error) {
+    out->Write({buf2}, [](auto bufs, uv::Error) {
       for (auto buf : bufs) {
         buf.Deallocate();
       }
diff --git a/wpiutil/src/netconsoleTee/native/cpp/main.cpp b/wpiutil/src/netconsoleTee/native/cpp/main.cpp
index 7053d9fc10..8abb458a03 100644
--- a/wpiutil/src/netconsoleTee/native/cpp/main.cpp
+++ b/wpiutil/src/netconsoleTee/native/cpp/main.cpp
@@ -48,7 +48,7 @@ static bool NewlineBuffer(std::string& rem, uv::Buffer& buf, size_t len,
                               static_cast<uint8_t>(ts & 0xff),
                               static_cast<uint8_t>((tcpSeq >> 8) & 0xff),
                               static_cast<uint8_t>(tcpSeq & 0xff)};
-    out << wpi::ArrayRef<uint8_t>(header);
+    out << wpi::span<const uint8_t>(header);
   }
   out << rem << toCopy;
 
@@ -114,7 +114,7 @@ static void CopyStream(uv::Stream& in, std::shared_ptr<uv::Stream> out) {
   in.data.connect([out](uv::Buffer& buf, size_t len) {
     uv::Buffer buf2 = buf.Dup();
     buf2.len = len;
-    out->Write(buf2, [](auto bufs, uv::Error) {
+    out->Write({buf2}, [](auto bufs, uv::Error) {
       for (auto buf : bufs) {
         buf.Deallocate();
       }
diff --git a/wpiutil/src/test/native/cpp/HttpWebSocketServerConnectionTest.cpp b/wpiutil/src/test/native/cpp/HttpWebSocketServerConnectionTest.cpp
index 0502950943..18a21be670 100644
--- a/wpiutil/src/test/native/cpp/HttpWebSocketServerConnectionTest.cpp
+++ b/wpiutil/src/test/native/cpp/HttpWebSocketServerConnectionTest.cpp
@@ -12,7 +12,7 @@ class HttpWebSocketServerConnectionTest
     : public HttpWebSocketServerConnection<HttpWebSocketServerConnectionTest> {
  public:
   HttpWebSocketServerConnectionTest(std::shared_ptr<uv::Stream> stream,
-                                    ArrayRef<std::string_view> protocols)
+                                    span<const std::string_view> protocols)
       : HttpWebSocketServerConnection{stream, protocols} {}
 
   void ProcessRequest() override { ++gotRequest; }
diff --git a/wpiutil/src/test/native/cpp/WebSocketClientTest.cpp b/wpiutil/src/test/native/cpp/WebSocketClientTest.cpp
index ceef954784..9d85e6676a 100644
--- a/wpiutil/src/test/native/cpp/WebSocketClientTest.cpp
+++ b/wpiutil/src/test/native/cpp/WebSocketClientTest.cpp
@@ -205,7 +205,7 @@ TEST_F(WebSocketClientTest, ProtocolReqNotResp) {
 
   clientPipe->Connect(pipeName, [&] {
     auto ws = WebSocket::CreateClient(*clientPipe, "/test", pipeName,
-                                      std::string_view{"myProtocol"});
+                                      {{"myProtocol"}});
     ws->closed.connect([&](uint16_t code, std::string_view msg) {
       Finish();
       ++gotClosed;
@@ -254,7 +254,7 @@ TEST_P(WebSocketClientDataTest, SendBinary) {
   std::vector<uint8_t> data(GetParam(), 0x03u);
   setupWebSocket = [&] {
     ws->open.connect([&](std::string_view) {
-      ws->SendBinary(uv::Buffer(data), [&](auto bufs, uv::Error) {
+      ws->SendBinary({{data}}, [&](auto bufs, uv::Error) {
         ++gotCallback;
         ws->Terminate();
         ASSERT_FALSE(bufs.empty());
@@ -275,7 +275,7 @@ TEST_P(WebSocketClientDataTest, ReceiveBinary) {
   int gotCallback = 0;
   std::vector<uint8_t> data(GetParam(), 0x03u);
   setupWebSocket = [&] {
-    ws->binary.connect([&](ArrayRef<uint8_t> inData, bool fin) {
+    ws->binary.connect([&](auto inData, bool fin) {
       ++gotCallback;
       ws->Terminate();
       ASSERT_TRUE(fin);
@@ -284,9 +284,7 @@ TEST_P(WebSocketClientDataTest, ReceiveBinary) {
     });
   };
   auto message = BuildMessage(0x02, true, false, data);
-  connected = [&] {
-    conn->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
-  };
+  connected = [&] { conn->Write({{message}}, [&](auto bufs, uv::Error) {}); };
 
   loop->Run();
 
@@ -311,9 +309,7 @@ TEST_P(WebSocketClientDataTest, ReceiveMasked) {
     });
   };
   auto message = BuildMessage(0x01, true, true, data);
-  connected = [&] {
-    conn->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
-  };
+  connected = [&] { conn->Write({{message}}, [&](auto bufs, uv::Error) {}); };
 
   loop->Run();
 
diff --git a/wpiutil/src/test/native/cpp/WebSocketIntegrationTest.cpp b/wpiutil/src/test/native/cpp/WebSocketIntegrationTest.cpp
index 54112c286c..3de75d995a 100644
--- a/wpiutil/src/test/native/cpp/WebSocketIntegrationTest.cpp
+++ b/wpiutil/src/test/native/cpp/WebSocketIntegrationTest.cpp
@@ -87,7 +87,7 @@ TEST_F(WebSocketIntegrationTest, ServerSendBinary) {
     auto conn = serverPipe->Accept();
     auto server = WebSocketServer::Create(*conn);
     server->connected.connect([&](std::string_view, WebSocket& ws) {
-      ws.SendBinary(uv::Buffer{"\x03\x04", 2}, [&](auto, uv::Error) {});
+      ws.SendBinary({uv::Buffer{"\x03\x04", 2}}, [&](auto, uv::Error) {});
       ws.Close();
     });
   });
@@ -100,7 +100,7 @@ TEST_F(WebSocketIntegrationTest, ServerSendBinary) {
         FAIL() << "Code: " << code << " Reason: " << reason;
       }
     });
-    ws->binary.connect([&](ArrayRef<uint8_t> data, bool) {
+    ws->binary.connect([&](auto data, bool) {
       ++gotData;
       std::vector<uint8_t> recvData{data.begin(), data.end()};
       std::vector<uint8_t> expectData{0x03, 0x04};
@@ -136,7 +136,7 @@ TEST_F(WebSocketIntegrationTest, ClientSendText) {
       }
     });
     ws->open.connect([&, s = ws.get()](std::string_view) {
-      s->SendText(uv::Buffer{"hello"}, [&](auto, uv::Error) {});
+      s->SendText({{"hello"}}, [&](auto, uv::Error) {});
       s->Close();
     });
   });
diff --git a/wpiutil/src/test/native/cpp/WebSocketServerTest.cpp b/wpiutil/src/test/native/cpp/WebSocketServerTest.cpp
index cd9dbba957..83561bf1ab 100644
--- a/wpiutil/src/test/native/cpp/WebSocketServerTest.cpp
+++ b/wpiutil/src/test/native/cpp/WebSocketServerTest.cpp
@@ -126,7 +126,7 @@ TEST_F(WebSocketServerTest, CloseBasic) {
   // need to respond with close for server to finish shutdown
   auto message = BuildMessage(0x08, true, true, {});
   handleData = [&](std::string_view) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   };
 
   loop->Run();
@@ -149,7 +149,7 @@ TEST_F(WebSocketServerTest, CloseCode) {
   const uint8_t contents[] = {0x03u, 0xe8u};
   auto message = BuildMessage(0x08, true, true, contents);
   handleData = [&](std::string_view) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   };
 
   loop->Run();
@@ -173,7 +173,7 @@ TEST_F(WebSocketServerTest, CloseReason) {
   const uint8_t contents[] = {0x03u, 0xe8u, 'h', 'a', 'n', 'g', 'u', 'p'};
   auto message = BuildMessage(0x08, true, true, contents);
   handleData = [&](std::string_view) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   };
 
   loop->Run();
@@ -197,7 +197,7 @@ TEST_F(WebSocketServerTest, ReceiveCloseBasic) {
   };
   auto message = BuildMessage(0x08, true, true, {});
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -219,7 +219,7 @@ TEST_F(WebSocketServerTest, ReceiveCloseCode) {
   const uint8_t contents[] = {0x03u, 0xe8u};
   auto message = BuildMessage(0x08, true, true, contents);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -242,7 +242,7 @@ TEST_F(WebSocketServerTest, ReceiveCloseReason) {
   const uint8_t contents[] = {0x03u, 0xe8u, 'h', 'a', 'n', 'g', 'u', 'p'};
   auto message = BuildMessage(0x08, true, true, contents);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -278,7 +278,7 @@ TEST_P(WebSocketServerBadOpcodeTest, Receive) {
   };
   auto message = BuildMessage(GetParam(), true, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -309,7 +309,7 @@ TEST_P(WebSocketServerControlFrameTest, ReceiveFragment) {
   };
   auto message = BuildMessage(GetParam(), false, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -336,7 +336,7 @@ TEST_F(WebSocketServerTest, ReceiveFragmentInvalidNoPrevFrame) {
   };
   auto message = BuildMessage(0x00, false, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -357,8 +357,7 @@ TEST_F(WebSocketServerTest, ReceiveFragmentInvalidNoPrevFragment) {
   auto message = BuildMessage(0x01, true, true, {});  // FIN=1
   auto message2 = BuildMessage(0x00, false, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write({uv::Buffer(message), uv::Buffer(message2)},
-                      [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}, {message2}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -379,9 +378,8 @@ TEST_F(WebSocketServerTest, ReceiveFragmentInvalidIncomplete) {
   auto message2 = BuildMessage(0x00, false, true, {});
   auto message3 = BuildMessage(0x01, true, true, {});
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(
-        {uv::Buffer(message), uv::Buffer(message2), uv::Buffer(message3)},
-        [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}, {message2}, {message3}},
+                      [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -401,7 +399,7 @@ TEST_F(WebSocketServerTest, ReceiveFragment) {
   combData.insert(combData.end(), data3.begin(), data3.end());
 
   setupWebSocket = [&] {
-    ws->binary.connect([&](ArrayRef<uint8_t> inData, bool fin) {
+    ws->binary.connect([&](auto inData, bool fin) {
       ++gotCallback;
       ws->Terminate();
       ASSERT_TRUE(fin);
@@ -414,9 +412,8 @@ TEST_F(WebSocketServerTest, ReceiveFragment) {
   auto message2 = BuildMessage(0x00, false, true, data2);
   auto message3 = BuildMessage(0x00, true, true, data3);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(
-        {uv::Buffer(message), uv::Buffer(message2), uv::Buffer(message3)},
-        [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}, {message2}, {message3}},
+                      [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -437,7 +434,7 @@ TEST_F(WebSocketServerTest, ReceiveFragmentSeparate) {
 
   setupWebSocket = [&] {
     ws->SetCombineFragments(false);
-    ws->binary.connect([&](ArrayRef<uint8_t> inData, bool fin) {
+    ws->binary.connect([&](auto inData, bool fin) {
       std::vector<uint8_t> recvData{inData.begin(), inData.end()};
       switch (++gotCallback) {
         case 1:
@@ -464,9 +461,8 @@ TEST_F(WebSocketServerTest, ReceiveFragmentSeparate) {
   auto message2 = BuildMessage(0x00, false, true, data2);
   auto message3 = BuildMessage(0x00, true, true, data3);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(
-        {uv::Buffer(message), uv::Buffer(message2), uv::Buffer(message3)},
-        [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}, {message2}, {message3}},
+                      [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -495,7 +491,7 @@ TEST_F(WebSocketServerTest, ReceiveTooLarge) {
   };
   auto message = BuildMessage(0x01, true, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -521,8 +517,7 @@ TEST_F(WebSocketServerTest, ReceiveTooLargeFragmented) {
   auto message = BuildMessage(0x01, false, true, data);
   auto message2 = BuildMessage(0x00, true, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write({uv::Buffer(message), uv::Buffer(message2)},
-                      [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}, {message2}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -545,7 +540,7 @@ TEST_P(WebSocketServerDataTest, SendText) {
   std::vector<uint8_t> data(GetParam(), ' ');
   setupWebSocket = [&] {
     ws->open.connect([&](std::string_view) {
-      ws->SendText(uv::Buffer(data), [&](auto bufs, uv::Error) {
+      ws->SendText({{data}}, [&](auto bufs, uv::Error) {
         ++gotCallback;
         ws->Terminate();
         ASSERT_FALSE(bufs.empty());
@@ -566,7 +561,7 @@ TEST_P(WebSocketServerDataTest, SendBinary) {
   std::vector<uint8_t> data(GetParam(), 0x03u);
   setupWebSocket = [&] {
     ws->open.connect([&](std::string_view) {
-      ws->SendBinary(uv::Buffer(data), [&](auto bufs, uv::Error) {
+      ws->SendBinary({{data}}, [&](auto bufs, uv::Error) {
         ++gotCallback;
         ws->Terminate();
         ASSERT_FALSE(bufs.empty());
@@ -587,7 +582,7 @@ TEST_P(WebSocketServerDataTest, SendPing) {
   std::vector<uint8_t> data(GetParam(), 0x03u);
   setupWebSocket = [&] {
     ws->open.connect([&](std::string_view) {
-      ws->SendPing(uv::Buffer(data), [&](auto bufs, uv::Error) {
+      ws->SendPing({{data}}, [&](auto bufs, uv::Error) {
         ++gotCallback;
         ws->Terminate();
         ASSERT_FALSE(bufs.empty());
@@ -608,7 +603,7 @@ TEST_P(WebSocketServerDataTest, SendPong) {
   std::vector<uint8_t> data(GetParam(), 0x03u);
   setupWebSocket = [&] {
     ws->open.connect([&](std::string_view) {
-      ws->SendPong(uv::Buffer(data), [&](auto bufs, uv::Error) {
+      ws->SendPong({{data}}, [&](auto bufs, uv::Error) {
         ++gotCallback;
         ws->Terminate();
         ASSERT_FALSE(bufs.empty());
@@ -639,7 +634,7 @@ TEST_P(WebSocketServerDataTest, ReceiveText) {
   };
   auto message = BuildMessage(0x01, true, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -651,7 +646,7 @@ TEST_P(WebSocketServerDataTest, ReceiveBinary) {
   int gotCallback = 0;
   std::vector<uint8_t> data(GetParam(), 0x03u);
   setupWebSocket = [&] {
-    ws->binary.connect([&](ArrayRef<uint8_t> inData, bool fin) {
+    ws->binary.connect([&](auto inData, bool fin) {
       ++gotCallback;
       ws->Terminate();
       ASSERT_TRUE(fin);
@@ -661,7 +656,7 @@ TEST_P(WebSocketServerDataTest, ReceiveBinary) {
   };
   auto message = BuildMessage(0x02, true, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -673,7 +668,7 @@ TEST_P(WebSocketServerDataTest, ReceivePing) {
   int gotCallback = 0;
   std::vector<uint8_t> data(GetParam(), 0x03u);
   setupWebSocket = [&] {
-    ws->ping.connect([&](ArrayRef<uint8_t> inData) {
+    ws->ping.connect([&](auto inData) {
       ++gotCallback;
       ws->Terminate();
       std::vector<uint8_t> recvData{inData.begin(), inData.end()};
@@ -682,7 +677,7 @@ TEST_P(WebSocketServerDataTest, ReceivePing) {
   };
   auto message = BuildMessage(0x09, true, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -694,7 +689,7 @@ TEST_P(WebSocketServerDataTest, ReceivePong) {
   int gotCallback = 0;
   std::vector<uint8_t> data(GetParam(), 0x03u);
   setupWebSocket = [&] {
-    ws->pong.connect([&](ArrayRef<uint8_t> inData) {
+    ws->pong.connect([&](auto inData) {
       ++gotCallback;
       ws->Terminate();
       std::vector<uint8_t> recvData{inData.begin(), inData.end()};
@@ -703,7 +698,7 @@ TEST_P(WebSocketServerDataTest, ReceivePong) {
   };
   auto message = BuildMessage(0x0a, true, true, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
@@ -730,7 +725,7 @@ TEST_P(WebSocketServerDataTest, ReceiveUnmasked) {
   };
   auto message = BuildMessage(0x01, true, false, data);
   resp.headersComplete.connect([&](bool) {
-    clientPipe->Write(uv::Buffer(message), [&](auto bufs, uv::Error) {});
+    clientPipe->Write({{message}}, [&](auto bufs, uv::Error) {});
   });
 
   loop->Run();
diff --git a/wpiutil/src/test/native/cpp/WebSocketTest.cpp b/wpiutil/src/test/native/cpp/WebSocketTest.cpp
index 18a3ccab62..b5d5e4e929 100644
--- a/wpiutil/src/test/native/cpp/WebSocketTest.cpp
+++ b/wpiutil/src/test/native/cpp/WebSocketTest.cpp
@@ -48,7 +48,7 @@ std::vector<uint8_t> WebSocketTest::BuildHeader(uint8_t opcode, bool fin,
 
 std::vector<uint8_t> WebSocketTest::BuildMessage(uint8_t opcode, bool fin,
                                                  bool masking,
-                                                 ArrayRef<uint8_t> data) {
+                                                 span<const uint8_t> data) {
   auto finalData = BuildHeader(opcode, fin, masking, data.size());
   size_t headerSize = finalData.size();
   finalData.insert(finalData.end(), data.begin(), data.end());
@@ -68,7 +68,7 @@ std::vector<uint8_t> WebSocketTest::BuildMessage(uint8_t opcode, bool fin,
 
 // If the message is masked, changes the mask to match the mask set by
 // BuildHeader() by unmasking and remasking.
-void WebSocketTest::AdjustMasking(MutableArrayRef<uint8_t> message) {
+void WebSocketTest::AdjustMasking(span<uint8_t> message) {
   if (message.size() < 2) {
     return;
   }
@@ -91,7 +91,7 @@ void WebSocketTest::AdjustMasking(MutableArrayRef<uint8_t> message) {
   message[maskPos + 2] = testMask[2];
   message[maskPos + 3] = testMask[3];
   int n = 0;
-  for (auto& ch : message.slice(maskPos + 4)) {
+  for (auto& ch : message.subspan(maskPos + 4)) {
     ch ^= mask[n] ^ testMask[n];
     if (++n >= 4) {
       n = 0;
diff --git a/wpiutil/src/test/native/cpp/WebSocketTest.h b/wpiutil/src/test/native/cpp/WebSocketTest.h
index 6063dc4051..fda4473d69 100644
--- a/wpiutil/src/test/native/cpp/WebSocketTest.h
+++ b/wpiutil/src/test/native/cpp/WebSocketTest.h
@@ -9,7 +9,7 @@
 #include <vector>
 
 #include "gtest/gtest.h"
-#include "wpi/ArrayRef.h"
+#include "wpi/span.h"
 #include "wpi/uv/Loop.h"
 #include "wpi/uv/Pipe.h"
 #include "wpi/uv/Timer.h"
@@ -58,8 +58,8 @@ class WebSocketTest : public ::testing::Test {
                                           bool masking, uint64_t len);
   static std::vector<uint8_t> BuildMessage(uint8_t opcode, bool fin,
                                            bool masking,
-                                           ArrayRef<uint8_t> data);
-  static void AdjustMasking(MutableArrayRef<uint8_t> message);
+                                           span<const uint8_t> data);
+  static void AdjustMasking(span<uint8_t> message);
   static const uint8_t testMask[4];
 
   std::shared_ptr<uv::Loop> loop;
diff --git a/wpiutil/src/test/native/cpp/json/unit-readme.cpp b/wpiutil/src/test/native/cpp/json/unit-readme.cpp
index ecb7f79ff1..14d2b1bb5f 100644
--- a/wpiutil/src/test/native/cpp/json/unit-readme.cpp
+++ b/wpiutil/src/test/native/cpp/json/unit-readme.cpp
@@ -200,7 +200,7 @@ TEST(JsonReadmeTest, OtherContainer)
 {
     std::vector<int> c_vector {1, 2, 3, 4};
     json j_vec(c_vector);
-    json j_vec2(wpi::makeArrayRef(c_vector));
+    json j_vec2(wpi::span<const int>(c_vector.data(), c_vector.size()));
     // [1, 2, 3, 4]
 
     std::deque<float> c_deque {1.2f, 2.3f, 3.4f, 5.6f};
diff --git a/wpiutil/src/test/native/cpp/span/test_conversions.cpp b/wpiutil/src/test/native/cpp/span/test_conversions.cpp
index 7f72b8dc89..fa111a770e 100644
--- a/wpiutil/src/test/native/cpp/span/test_conversions.cpp
+++ b/wpiutil/src/test/native/cpp/span/test_conversions.cpp
@@ -1,7 +1,7 @@
 #if __has_include(<span>)
 #include <span>
 #endif
-#include "wpi/ArrayRef.h"
+#include "wpi/span.h"
 
 #include "gtest/gtest.h"
 
@@ -9,17 +9,13 @@ void func1(wpi::span<const int> x) {}
 #ifdef __cpp_lib_span
 void func2(std::span<const int> x) {}
 #endif
-void func3(wpi::ArrayRef<int> x) {} 
 
 void func4(wpi::span<int> x) {}
 #ifdef __cpp_lib_span
 void func5(std::span<int> x) {}
 #endif
-void func6(wpi::MutableArrayRef<int> x) {} 
 
-TEST(Span, ConvertArrayRefStdSpan) {
-  func1(wpi::ArrayRef<int>{});
-  func1(wpi::MutableArrayRef<int>{});
+TEST(Span, ConvertStdSpan) {
   func1(wpi::span<const int>{});
   func1(wpi::span<int>{});
 #ifdef __cpp_lib_span
@@ -28,25 +24,12 @@ TEST(Span, ConvertArrayRefStdSpan) {
 #endif
 
 #ifdef __cpp_lib_span
-  func2(wpi::ArrayRef<int>{});
-  func2(wpi::MutableArrayRef<int>{});
   func2(wpi::span<const int>{});
   func2(wpi::span<int>{});
   func2(std::span<const int>{});
   func2(std::span<int>{});
 #endif
 
-  func3(wpi::ArrayRef<int>{});
-  func3(wpi::MutableArrayRef<int>{});
-  func3(wpi::span<const int>{});
-  func3(wpi::span<int>{});
-#ifdef __cpp_lib_span
-  func3(std::span<const int>{});
-  func3(std::span<int>{});
-#endif
-
-  //func4(wpi::ArrayRef<int>{});
-  func4(wpi::MutableArrayRef<int>{});
   //func4(wpi::span<const int>{});
   func4(wpi::span<int>{});
 #ifdef __cpp_lib_span
@@ -55,20 +38,9 @@ TEST(Span, ConvertArrayRefStdSpan) {
 #endif
 
 #ifdef __cpp_lib_span
-  //func5(wpi::ArrayRef<int>{});
-  func5(wpi::MutableArrayRef<int>{});
   //func5(wpi::span<const int>{});
   func5(wpi::span<int>{});
   //func5(std::span<const int>{});
   func5(std::span<int>{});
 #endif
-
-  //func6(wpi::ArrayRef<int>{});
-  func6(wpi::MutableArrayRef<int>{});
-  //func6(wpi::span<const int>{});
-  func6(wpi::span<int>{});
-#ifdef __cpp_lib_span
-  //func6(std::span<const int>{});
-  func6(std::span<int>{});
-#endif
 }
diff --git a/wpiutil/src/test/native/cpp/uv/UvBufferTest.cpp b/wpiutil/src/test/native/cpp/uv/UvBufferTest.cpp
index 89f08d026a..4faeaf8b7f 100644
--- a/wpiutil/src/test/native/cpp/uv/UvBufferTest.cpp
+++ b/wpiutil/src/test/native/cpp/uv/UvBufferTest.cpp
@@ -26,7 +26,7 @@ TEST(UvSimpleBufferPool, ReleaseReuse) {
   auto buf1copy = buf1;
   auto origSize = buf1.len;
   buf1.len = 8;
-  pool.Release(buf1);
+  pool.Release({&buf1, 1});
   ASSERT_EQ(buf1.base, nullptr);
   auto buf2 = pool.Allocate();
   ASSERT_EQ(buf1copy.base, buf2.base);
@@ -36,7 +36,7 @@ TEST(UvSimpleBufferPool, ReleaseReuse) {
 TEST(UvSimpleBufferPool, ClearRemaining) {
   SimpleBufferPool<4> pool;
   auto buf1 = pool.Allocate();
-  pool.Release(buf1);
+  pool.Release({&buf1, 1});
   ASSERT_EQ(pool.Remaining(), 1u);
   pool.Clear();
   ASSERT_EQ(pool.Remaining(), 0u);