Build Status

A Dart-JavaScript interoperability for Alexa Web API for Games. Alexa Web API for Games lets you create rich, immersive voice-enabled games by combining Alexa Skills Kit (ASK) directives with familiar web technologies.


Alexa Objects - Client

Property Description Supported
capabilities The device capabilities.
For details, see Microphone and Capability.
performance Provides the interface to get the available memory on the device.
For details, see Performance.
skill Provides the interfaces to communicate with your skill.
For details, see onMessage and sendMessage.
speech Provides the interfaces to receive Alexa speech events.
For details, see Alexa Speech Input.
version Version of the Alexa client.
If you don't specify a version, the latest version is used.
voice Provides the interfaces to open the microphone on the device to receive user utterances.
For details, see Alexa Voice.


Property Description Supported
create Establish the connection to Alexa on the device. When the future is completed successfully, an AlexaReadyPayload object is returned. Otherwise, when the future completes with an error, an ErrorWithCode object is returned. For details, see create. ➖ *

*Even though a MessageProvider can be passed as an parameter in the Alexa.create function, doing this will cause an exception to be thrown.


Property Description Supported
Entity-Sensing Alexa-enabled devices with entity-sensing capabilities can detect the presence of the user.
For details, see Entity-Sensing.
Smart-Motion Alexa-enabled devices with smart-motion capabilities can rotate the device screen to turn toward and follow engaged users.
For details, see Smart-Motion.

✅ Supported

❌ Not supported

➖ Partially supported


Add the Alexa JavaScript library to your app

To load the Alexa JavaScript library, include the URL in a script tag on your HTML page, as shown in the following example.

  <script src=""></script>

Create the Alexa client

Your app communicates with the device and with your skill with the Alexa Client object. To prevent the client from being available before it's ready to serve requests, create the Alexa Client object with a static factory function. Invoke the function one time on each page.

The following example shows Alexa Client object initialization.

Alexa.create(CreateClientOptions(version: '1.1')).then((args) {
  AlexaReadyPayload alexaClient = args.alexa;
  querySelector('#debugElement')?.innerHtml = 'Alexa is ready :)';
}).onError((ErrorWithCode error, stackTrace) {
  querySelector('#debugElement')?.innerHtml = 'Alexa not ready :(';


Check the device capabilities using the capabilities interface.

The following example shows a check for PushToTalk capability using a Microphoneobject.

if (alexaClient.capabilities.microphone.supportsPushToTalk) {
  // Prompt the user to press the microphone button

The following example shows a check for WakeWord capability using a Microphoneobject.

if (alexaClient.capabilities.microphone.supportsWakeWord) {
  // Prompt the user to press the microphone button


Use the performance interface to get the available memory on the device. This interface is useful in development for optimizing assets and debugging across device types.

Important: Don't use the performance interface in production because the invocation can negatively affect device performance.

The following example shows logging the available memory.

alexaClient.performance.getMemoryInfo().then((memInfo) => {
  // log memInfo
}).onError((MemoryInfoError error, stackTrace) {
  // log error caused by memInfo


Use the alexaClient.skill.onMessage to register a listener to handle messages sent from your skill. The messages sent to your listener are independent of the messages your app sends to your skill. The format of the message sent from the skill is agreed on between the app and the skill. The app can only register one callback, so the callback function should include logic to handle different messages based on the data provided within the message. Messages can't be received until you register the listener. If you need information from the skill on start-up, use the message returned in the successful create interface.

The following example shows registering a listener function called messageReceivedCallback.

main() {
  // Register a listener to receive a message from your skill

// Implement the listener
void _messageReceivedCallback(dynamic message) {
  // Process message (JavaScript object) from your skill


To send a message to your skill from your web app, use alexaClient.skill.sendMessage interface. The interface takes a data payload and an optional callback for handling the response. The API results in an Alexa.Presentation.HTML.Message to your skill.

Important: You can't send more than two messages per second to the skill. Use the optional callback on alexa.skill.sendMessage() to catch throttling errors caused when your app exceeds this limit. The MessageSendResponse returns error 429 (Too Many Requests) to your callback.

The following example shows sending a message to the skill.

main() {
  // Send a message to your skill
  alexaClient.skill.sendMessage(message, allowInterop(_messageSentCallback));

// Check the results of the MessageSendResponse
void _messageReceivedCallback(MessageSendResponse sendResponse) {
  // Handle response codes

Known Issues

Contributing to this package

If you would like to contribute to the plugin, check out our contribution guide.


This is not an Amazon product.