Configure an Implicit Grant
The Alexa Skills Kit supports implicit grants for account linking in custom skills. You cannot use this grant type for other types of skills, such as smart home skills.
- Overview of the implicit grant flow
- Steps to configure an implicit grant
- Authorization URI
- Access tokens
- Configure account linking
- Test the account linking flow
- Related topics
Overview of the implicit grant flow
Users can start the account linking process when enabling the skill, or from a link account card in the Alexa app. For more about how users interact with account linking, see Account Linking for Custom Skills.
The user starts the process by enabling the skill in the Alexa app or tapping a link on the link account card.
The Alexa app displays a login page within the app, using the authorization URI you provide when you configure account linking. This login page lets the user authenticate with the authorization server.
When the Alexa app calls the specified authorization URI, it includes
redirect_urias query string parameters.
- The user logs in using their credentials for the authorization server.
- Once the user is authenticated, the authorization server generates an access token (
access_token) that uniquely identifies the user.
- The authorization server redirects the user to the specified
redirect_uriand passes along the
token_typein the URL fragment.
The Alexa service saves the
access_tokenfor the Alexa user.
The user's Alexa account is now linked to the account in your service, and the skill is ready for use.
- When the user makes requests to the skill, every request sent to the skill (such as an
IntentRequest) now includes the access token (
access_token). Your skill uses this token to get the information you need from the resource server.
The following diagram illustrates the initial setup when the user links their account and Alexa obtains the access token from your authorization server.
This diagram shows the flow when the user makes a request to the skill and the skill then uses the access token to retrieve information from the resource server.
Steps to configure an implicit grant
- Make sure that you have an authorization server that meets the requirements described in Requirements for Account Linking for Alexa Skills.
- Configure your skill for the implicit grant type in the developer portal. For details, see Configure Account Linking in the Developer Console.
After you configure the implicit grant, move on to the next step and add the logic to validate and use the access token to your skill code. For more information, see:
When a user starts the process of linking accounts, the Alexa app displays a login page for the authorization server. The authorization server needs to validate the user's credentials and then return an access token.
You specify the URL for this login page in the developer console on the Build > Account Linking page. You provide the URL for the login page in the Authorization URI field.
If you use a third-party OAuth provider, see the documentation for that provider to determine the authorization URI you need when you configure account linking. Look for the URI for an authorization request.
Parameters passed to the authorization URI
The Alexa app includes the following parameters in the URL query string when it calls your authorization URI.
An identifier for your skill. You can use this to provide any skill-specific functionality, such as distinguishing between different skills you have configured with account linking. You define the
The Amazon-specific redirection endpoint (redirect URL) to which the service should redirect the user after authenticating the user. The values you can expect for this parameter are also displayed in the developer console when you configure account linking for your skill.
Indicates the type of response that should be returned after the user has been authenticated by the other service. This is always
An optional list of scopes indicating the access the Alexa user needs. You define these scopes when you configure account linking for your skill for your skill.
A value used internally by the Alexa service to track the user through the account linking process.
The Alexa app sends a
Your authorization server needs to provide an access token that uniquely identifies a user. Your skill can then use this token to access information about the user in your resource server.
The Alexa service calls the access token endpoint for your authorization server (specified as the Access Token URI in the developer console) and passes the client ID in a POST request. The authorization server returns the access token in a JSON response.
Example access token request:
POST /auth/o2/token HTTP/1.1
Example access token response:
HTTP/1.1 200 OK
Content-Type: application/json;charset UTF-8
For access token requirements, see Access token URI requirements.
When generating the access token, provide a token specific to your resource server. For security, your token should be a value that identifies the user, but cannot be guessed.
Configure account linking
The following table summarizes the fields you must fill in to configure account linking. If you use a third-party OAuth provider, see the documentation for that provider to determine the values to enter in these fields.
Do you allow users to create an account or link to an existing account with you?
Select this to enable account linking for a custom skill. This option is automatically selected for smart home and video skills.
Allow users to enable the skill without account linking
Select this to let users bypass the account linking flow when they enable your skill. Available for custom skills only. This is useful if your skill offers meaningful functionality without an account, in addition to the features that require an account. See Let Users Enable Your Skill without Account Linking.
This option is on by default.
Authorization Grant Type
The OAuth 2.0 authorization grant type to use to obtain the access token. Select Implicit Grant.
The URI for a page the user can use to log into your service. The Alexa app displays this page when the user begins the account linking process. Refer back to Authorization URI for details and requirements.
For a third-party OAuth provider, look for the URI provided for authorization requests. For example, for Login with Amazon, the authorization URI is
Your Client ID
A unique string that identifies the client requesting authentication. This value is passed to the authorization URI in the
For a third-party OAuth provider, look for the client identifier that the provider expects. For example, for Login with Amazon, this ID is created when you create a security profile for Login with Amazon.
An optional list of permissions for the other service. If your resource server supports different scopes for access, enter those here. You can provide up to 15 scopes.
All of the scopes entered here are included in the
For a third-party OAuth provider, specify a scope from the set of scopes that the provider supports. For example, Login with Amazon supports
An optional list of domains that the authorization URI can retrieve data from. If your login page retrieves content from other domains, enter those in this list.
This is only necessary for domains beyond your authorization URI. For example, suppose your authorization URI is
Alexa Redirect URLs
This displays the Amazon-provided redirection endpoints to which your login page must redirect the user after the user is authenticated. The value to use for a given request is passed to your login page as the
Alexa Redirect URLs
You can see the redirection endpoints that Alexa uses in the Alexa Redirect URLs field on the Build > Account Linking page in the developer console. This endpoint is the URL to which your log-in page must redirect the user after the user is authenticated.
Note that Alexa Redirect URLs displays multiple URIs. The Alexa app passes your authorization URI the value you should use based on where the user registered their device. The URI is passed to your authorization URI in the
You typically need to register the redirection endpoint with the authorization server to ensure that the authorization URI can call it, especially if don't own your authorization server. To ensure that your skill works from multiple regions, register all of the URIs shown in Your Redirect URLs.
How you do this depends on the authorization server you are using. For example, in Login with Amazon, you need to configure a security profile and provide the possible redirect URLs in the Allowed Return URLs field.
See the documentation for your OAuth provider to determine these requirements.
For example, the value passed in the
redirect_uri parameter for an implicit grant might look like this:
As noted in the authorization URI requirements, your authorization URI redirects the user to the
redirect_uri and includes
token_type in the URL fragment. For example:
Test the account linking flow
After you configure account linking, you can test the account linking flow. Use the Alexa app to enable your skill and start the account linking process. Verify that you can log in to the service and then return to the Alexa app.
To finish implementing account linking, you need to update your skill code to check for the access token on incoming requests and take appropriate actions. For details, see:
- Custom skills: Validate and Use Access Tokens in Custom Skill Code
- Smart home skills and other domains: Validate and Use Access Tokens in Smart Home and Video Skill Code
- Quick Reference: Add Account Linking to an Alexa Skill
- Account Linking for Custom Skills
- Account Linking Concepts for Alexa Skills
- The OAuth 2.0 Authorization Framework (RFC 6749)
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Last updated: Nov 15, 2023