diff --git a/doc/basic_env.md b/doc/basic_env.md
index 7a5b430f1..840a5480f 100644
--- a/doc/basic_env.md
+++ b/doc/basic_env.md
@@ -72,17 +72,18 @@ void SetInstanceData(DataType* data, HintType* hint) const;
 - `[template] fini`: A function to call when the instance data is to be deleted.
 Accepts a function of the form `void CleanupData(Napi::Env env, DataType* data,
 HintType* hint)`. If not given, the default finalizer will be used, which simply
-uses the `delete` operator to destroy `T*` when the add-on instance is unloaded.
+uses the `delete` operator to destroy `DataType*` when the add-on instance is
+unloaded.
 - `[in] data`: A pointer to data that will be associated with the instance of
 the add-on for the duration of its lifecycle.
 - `[in] hint`: A pointer to data that will be associated with the instance of
 the add-on for the duration of its lifecycle and will be passed as a hint to
 `fini` when the add-on instance is unloaded.
 
-Associates a data item stored at `T* data` with the current instance of the
-add-on. The item will be passed to the function `fini` which gets called when an
-instance of the add-on is unloaded. This overload accepts an additional hint to
-be passed to `fini`.
+Associates a data item stored at `DataType* data` with the current instance of
+the add-on. The item will be passed to the function `fini` which gets called
+when an instance of the add-on is unloaded. This overload accepts an additional
+hint to be passed to `fini`.
 
 ### GetModuleFileName
 
diff --git a/doc/external.md b/doc/external.md
index 4b4603e8e..1c48560b6 100644
--- a/doc/external.md
+++ b/doc/external.md
@@ -35,9 +35,8 @@ Returns the created `Napi::External<T>` object.
 
 ```cpp
 template <typename T>
-static Napi::External Napi::External::New(napi_env env,
-                    T* data,
-                    Finalizer finalizeCallback);
+template <typename Finalizer>
+static External New(napi_env env, T* data, Finalizer finalizeCallback);
 ```
 
 - `[in] env`: The `napi_env` environment in which to construct the `Napi::External` object.
@@ -52,7 +51,8 @@ Returns the created `Napi::External<T>` object.
 
 ```cpp
 template <typename T>
-static Napi::External Napi::External::New(napi_env env,
+template <typename Finalizer, typename Hint>
+static External New(napi_env env,
                     T* data,
                     Finalizer finalizeCallback,
                     Hint* finalizeHint);
diff --git a/doc/threadsafe_function.md b/doc/threadsafe_function.md
index fcbc2dff1..9ab404731 100644
--- a/doc/threadsafe_function.md
+++ b/doc/threadsafe_function.md
@@ -70,9 +70,9 @@ New(napi_env env,
   opportunity for cleaning up after the threads e.g. by calling
   `uv_thread_join()`. It is important that, aside from the main loop thread,
   there be no threads left using the thread-safe function after the finalize
-  callback completes. Must implement `void operator()(Env env, DataType* data,
-  ContextType* hint)`, skipping `data` or `hint` if they are not provided. Can
-  be retrieved via `GetContext()`.
+  callback completes. Must implement `void operator()(Env env,
+  FinalizerDataType* data, ContextType* context)`, skipping `data` or `context`
+  if they are not provided. Can be retrieved via `GetContext()`.
 - `[optional] data`: Data to be passed to `finalizeCallback`.
 
 Returns a non-empty `Napi::ThreadSafeFunction` instance.
diff --git a/doc/typed_threadsafe_function.md b/doc/typed_threadsafe_function.md
index 74d3cc2ed..6dcc0343e 100644
--- a/doc/typed_threadsafe_function.md
+++ b/doc/typed_threadsafe_function.md
@@ -82,7 +82,7 @@ New(napi_env env,
   calling `uv_thread_join()`. It is important that, aside from the main loop
   thread, there be no threads left using the thread-safe function after the
   finalize callback completes. Must implement `void operator()(Env env,
-  FinalizerDataType* data, ContextType* hint)`.
+  FinalizerDataType* data, ContextType* context)`.
 - `[optional] data`: Data to be passed to `finalizeCallback`.
 
 Returns a non-empty `Napi::TypedThreadSafeFunction` instance.
diff --git a/napi.h b/napi.h
index 870a5c290..486f44c0f 100644
--- a/napi.h
+++ b/napi.h
@@ -422,12 +422,16 @@ class BasicEnv {
 #endif  // NAPI_VERSION > 8
 
 #ifdef NODE_API_EXPERIMENTAL_HAS_POST_FINALIZER
+  // FinalizerType must implement `void operator()(Env env)`.
   template <typename FinalizerType>
   inline void PostFinalizer(FinalizerType finalizeCallback) const;
 
+  // FinalizerType must implement `void operator()(Env env, T* data)`.
   template <typename FinalizerType, typename T>
   inline void PostFinalizer(FinalizerType finalizeCallback, T* data) const;
 
+  // FinalizerType must implement `void operator()(Env env, T* data,
+  // Hint* hint)`.
   template <typename FinalizerType, typename T, typename Hint>
   inline void PostFinalizer(FinalizerType finalizeCallback,
                             T* data,
@@ -1107,9 +1111,12 @@ class Object : public TypeTaggable {
       const Function& constructor  ///< Constructor function
   ) const;
 
+  // Finalizer must implement `void operator()(Env env, T* data)`.
   template <typename Finalizer, typename T>
   inline void AddFinalizer(Finalizer finalizeCallback, T* data) const;
 
+  // Finalizer must implement `void operator()(Env env, T* data,
+  // Hint* hint)`.
   template <typename Finalizer, typename T, typename Hint>
   inline void AddFinalizer(Finalizer finalizeCallback,
                            T* data,
@@ -1157,7 +1164,8 @@ class External : public TypeTaggable {
   // Finalizer must implement `void operator()(Env env, T* data)`.
   template <typename Finalizer>
   static External New(napi_env env, T* data, Finalizer finalizeCallback);
-  // Finalizer must implement `void operator()(Env env, T* data, Hint* hint)`.
+  // Finalizer must implement `void operator()(Env env, T* data,
+  // Hint* hint)`.
   template <typename Finalizer, typename Hint>
   static External New(napi_env env,
                       T* data,
@@ -1712,7 +1720,8 @@ class Buffer : public Uint8Array {
                        T* data,
                        size_t length,
                        Finalizer finalizeCallback);
-  // Finalizer must implement `void operator()(Env env, T* data, Hint* hint)`.
+  // Finalizer must implement `void operator()(Env env, T* data,
+  // Hint* hint)`.
   template <typename Finalizer, typename Hint>
   static Buffer<T> New(napi_env env,
                        T* data,
@@ -1728,7 +1737,8 @@ class Buffer : public Uint8Array {
                              T* data,
                              size_t length,
                              Finalizer finalizeCallback);
-  // Finalizer must implement `void operator()(Env env, T* data, Hint* hint)`.
+  // Finalizer must implement `void operator()(Env env, T* data,
+  // Hint* hint)`.
   template <typename Finalizer, typename Hint>
   static Buffer<T> NewOrCopy(napi_env env,
                              T* data,
@@ -2825,6 +2835,7 @@ class ThreadSafeFunction {
                                 ContextType* context);
 
   // This API may only be called from the main thread.
+  // Finalizer must implement `void operator()(Env env)`.
   template <typename ResourceString, typename Finalizer>
   static ThreadSafeFunction New(napi_env env,
                                 const Function& callback,
@@ -2834,6 +2845,8 @@ class ThreadSafeFunction {
                                 Finalizer finalizeCallback);
 
   // This API may only be called from the main thread.
+  // Finalizer must implement
+  // `void operator()(Env env, FinalizerDataType* data)`.
   template <typename ResourceString,
             typename Finalizer,
             typename FinalizerDataType>
@@ -2846,6 +2859,8 @@ class ThreadSafeFunction {
                                 FinalizerDataType* data);
 
   // This API may only be called from the main thread.
+  // Finalizer must implement
+  // `void operator()(Env env, ContextType* context)`.
   template <typename ResourceString, typename ContextType, typename Finalizer>
   static ThreadSafeFunction New(napi_env env,
                                 const Function& callback,
@@ -2856,6 +2871,8 @@ class ThreadSafeFunction {
                                 Finalizer finalizeCallback);
 
   // This API may only be called from the main thread.
+  // Finalizer must implement `void operator()(Env env,
+  // FinalizerDataType* data, ContextType* context)`.
   template <typename ResourceString,
             typename ContextType,
             typename Finalizer,
@@ -2889,6 +2906,7 @@ class ThreadSafeFunction {
                                 ContextType* context);
 
   // This API may only be called from the main thread.
+  // Finalizer must implement `void operator()(Env env)`.
   template <typename ResourceString, typename Finalizer>
   static ThreadSafeFunction New(napi_env env,
                                 const Function& callback,
@@ -2899,6 +2917,8 @@ class ThreadSafeFunction {
                                 Finalizer finalizeCallback);
 
   // This API may only be called from the main thread.
+  // Finalizer must implement
+  // `void operator()(Env env, FinalizerDataType* data)`.
   template <typename ResourceString,
             typename Finalizer,
             typename FinalizerDataType>
@@ -2912,6 +2932,8 @@ class ThreadSafeFunction {
                                 FinalizerDataType* data);
 
   // This API may only be called from the main thread.
+  // Finalizer must implement
+  // `void operator()(Env env, ContextType* context)`.
   template <typename ResourceString, typename ContextType, typename Finalizer>
   static ThreadSafeFunction New(napi_env env,
                                 const Function& callback,
@@ -2923,6 +2945,8 @@ class ThreadSafeFunction {
                                 Finalizer finalizeCallback);
 
   // This API may only be called from the main thread.
+  // Finalizer must implement `void operator()(Env env,
+  // FinalizerDataType* data, ContextType* context)`.
   template <typename ResourceString,
             typename ContextType,
             typename Finalizer,
@@ -3067,6 +3091,8 @@ class TypedThreadSafeFunction {
   // This API may only be called from the main thread.
   // Creates a new threadsafe function with:
   //   Callback [missing] Resource [missing] Finalizer [passed]
+  // Finalizer must implement `void operator()(Env env,
+  // FinalizerDataType* data, ContextType* context)`.
   template <typename ResourceString,
             typename Finalizer,
             typename FinalizerDataType = void>
@@ -3082,6 +3108,8 @@ class TypedThreadSafeFunction {
   // This API may only be called from the main thread.
   // Creates a new threadsafe function with:
   //   Callback [missing] Resource [passed] Finalizer [passed]
+  // Finalizer must implement `void operator()(Env env,
+  // FinalizerDataType* data, ContextType* context)`.
   template <typename ResourceString,
             typename Finalizer,
             typename FinalizerDataType = void>
@@ -3124,6 +3152,8 @@ class TypedThreadSafeFunction {
   // This API may only be called from the main thread.
   // Creates a new threadsafe function with:
   //   Callback [passed] Resource [missing] Finalizer [passed]
+  // Finalizer must implement `void operator()(Env env,
+  // FinalizerDataType* data, ContextType* context)`.
   template <typename ResourceString,
             typename Finalizer,
             typename FinalizerDataType = void>
@@ -3140,6 +3170,8 @@ class TypedThreadSafeFunction {
   // This API may only be called from the main thread.
   // Creates a new threadsafe function with:
   //   Callback [passed] Resource [passed] Finalizer [passed]
+  // Finalizer must implement `void operator()(Env env,
+  // FinalizerDataType* data, ContextType* context)`.
   template <typename CallbackType,
             typename ResourceString,
             typename Finalizer,