Configure an Implicit Grant

The Alexa Skills Kit supports implicit grants for account linking in custom skills. You can’t use this grant type for other types of skills, such as smart home add-ons.

Implicit grant flow overview

Alexa uses the OAuth 2.0 account linking flow with implicit grant to link the user’s Amazon account with their account in your system. This flow is the same for both traditional account linking and app-to-app account linking starting from the Alexa app. In traditional account linking, Alexa uses the configured URI to open the login page on your website. In app-to-app account linking, Alexa uses the configured URI to open the login page in your app, or if the app isn’t installed on the device, Alexa uses the website URI as fall back. 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.

Link the account

The following steps describe implicit grant flow to link the user accounts.

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 state, client_id, response_type, scope, and redirect_uri as 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_uri and passes along the state, access_token, and token_type in the URL fragment.
The Alexa service saves the access_token for the Alexa user.

The user’s Alexa account is now linked to the account in your service, and the skill is ready for use. The following diagram shows the account linking flow when the user links their account from the Alexa app. Here, Alexa obtains the access token from your authorization server as described in steps 1–6.

Use the access token in your skill

When the user makes requests to the skill, each request, such as an IntentRequest, now includes the access_token. Your skill uses this token to get the information you need from the resource server. The following 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.

Skill uses the access token to request user resources. — Access token in skill interaction

Authorization URI details

You configure the authorization URL in the Alexa developer console on the Build > Account Linking page. You provide the URL in the Authorization URI field. The Alexa service passes parameters to your authorization server in the URL query string. For example, if the authorization URI for your page is https://www.ridehailer.com/login, Alexa sends the following parameters:

https://www.ridehailer.com/login?state=abc&client_id=unique-id&scope=order_car+basic_profile&response_type=token&redirect_uri=https://pitangui.amazon.com/api/skill/link/M2AAAAAAAAAAAA

The Alexa service includes the following parameters in the query string when it opens your authorization URI.

Parameter	Description
`client_id`	An identifier for your skill. You can use this value to provide any skill-specific functionality, such as distinguishing between different skills you have configured with account linking. You define the `client_id` when you configure account linking for your skill.
`redirect_uri`	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 Alexa developer console when you configure account linking for your skill.
`response_type`	Indicates the type of response to return after the user was authenticated by the authorization server. The `response_type` is always `token` for the implicit grant type.
`scope`	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. The token server can use this information when generating the access token. For example, the server can create a token that allows access to basic profile information in the resource server, but doesn’t allow access to payment information. Multiple scopes can be used. The list is delimited by URL-encoded spaces. The login page should tell users what access they’re allowing by linking their accounts. For instance, your login page might display text, such as “This allows the Ride Hailer skill to order a taxi on your behalf and charge your account for the cost.” For a smart home skill, the login page might display “This allows the My Lights skill to control lights connected to your My Lights hub.”
`state`	A value used internally by the Alexa service to track the user through the account linking process.The Alexa service sends a `state` value to your authorization server in the authorization URI. Your authorization server must use that same `state` value when it subsequently calls the redirect URI for that particular account linking request. Each request to the authorization server has its own `state` value.

Alexa redirect URLs details

You can find the redirection endpoints for the Alexa app in the Alexa Redirect URLs field on the Build > Account Linking page in the developer portal. These endpoints are the URLs to which your log-in page must redirect the user after the user authenticates with your server. The list shows multiple URLs, one for each Alexa region. Based on where the user registered their device, the Alexa app selects and passes the redirect URL with your authorization URI in the redirect_uri query parameter in the URL query string. Your server must use the redirect_uri to send the user back to the Alexa app after authentication. For example, if the redirect_uri parameter is https://pitangui.amazon.com/spa/skill/account-linking-status.html?vendorId=M2AAAAAAAAAAAA, your login page would redirect the user to the following URL. You include the state and access_token parameters as a URL fragment starting with #.

https://pitangui.amazon.com/spa/skill/account-linking-status.html?vendorId=vendor.id.1#state=xyz&access_token=sometoken.1&token_type=Bearer

Access tokens

You configure the access token endpoint for your authorization server in the Alexa developer console on the Build > Account Linking page by entering the appropriate URL in the Access Token URI field. After a user links their account, the Alexa service sends a POST request to the token URI containing the client credentials. Your authorization server should then generate and return an access token that uniquely identifies the user. This token should be specific to your resource server and created with security in mind. The token should identify the user but remain unguessable. For access token requirements, see Access token URI requirements. The following code shows an example access token request from Alexa.

POST /auth/o2/token HTTP/1.1
Host: api.amazon.com
Content-Type: application/x-www-form-urlencoded;charset=UTF-8

grant_type=implicit
&client_id=exampleId
&redirect_uri=https://pitangui.amazon.com/api/skill/link/M3PCA6K3O9X0NW

On successful generation of the access token, the authorization server might send the following example response.

HTTP/1.1 200 OK
Content-Type: application/json;charset UTF-8
Cache-Control: no-store
Pragma: no-cache
{
   "access_token":"Atza|EXAMPLEACCESSTOKEN123456...",
   "token_type":"bearer",
   "expires_in":3600
}

Prerequisites

Make sure that you have an authorization server that meets the requirements described in Requirements for Account Linking.

Steps to configure an implicit grant

Configure your skill for the implicit grant type in the Alexa developer portal. For details, see Configure Account Linking in the Alexa Developer Portal.
Add logic to validate and use the access token to your skill code.
Test the account linking flow.

Step 1: Configure account linking

You can turn on account linking in the Alexa developer console on the Build > Account Linking page. Or, you can configure account linking with the ASK CLI or the Account Linking REST API.

Account linking settings

Under Settings, you enable and disable the account linking options available to your skill. The service provider options in the next section are based on the settings that you enable here. The following table describes the settings fields to configure account linking.

Field	Description
Do you allow users to create an account or link to an existing account with you?	Turn on 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 (Recommended)	Turn on to let users bypass the account linking flow when they enable your skill. Available for custom skills only. This option is useful if your skill offers meaningful functionality without an account, in addition to the features that require an account. For more details, see Let Users Enable Your Skill without Account Linking.This option is on by default.
Allow users to link their account to your skill from within your application or website	Turn on to allow users to authenticate by using your website.
Allow users to authenticate using your mobile application	Turn on to enable app-to-app account linking and allow users to authenticate by using your mobile app.
Allow users to link their account to your skill using voice	Turn on to enable customers to use their voice to link their Amazon account with the account they have with your service.

Security provider information

Under Security provider information, select the authorization grant type, and then configure the service provider information as shown in the following table. The options displayed here are based on the settings that you enabled in the settings section. If you use a third-party OAuth provider, see the documentation for that provider to determine the values to enter in these fields.

Field	Description
Authorization Grant Type	The OAuth 2.0 authorization grant type to use to obtain the access token. Select Implicit Grant.
Your Web Authorization URI	The URI to open the authorization page on your website for the user to sign in to your service. The Alexa app displays the login page when the user begins the account linking process. For more details, see Authorization URI.For a third-party OAuth provider, look for the URI provided for authorization requests. For example, for the Login with Amazon (LWA) OAuth provider, the authorization URI is `https://www.amazon.com/ap/oa`.
Your iOS App Authorization URI	The Universal Link to open the authorization page in your iOS mobile app for the user to log into your service. The Alexa app opens the app when the user begins the account linking process from an iOS mobile app. For more details, see Authorization URI. Required when you enable authentication from your mobile app.
Your Android App Authorization URI	The App Link to open the authorization page in your Android mobile app for the user to log into your service. The Alexa app opens the app when the user begins the account linking process from an Android mobile app. For more details, see Authorization URI. Required when you enable authentication from your mobile app.
Your Client ID	A unique string that identifies the client requesting authentication. This value is passed to the authorization URI in the `client_id` parameter.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.
Scope	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.Alexa includes all of the scopes entered here in the `scope` parameter (separated by URL-encoded spaces) when the Alexa app calls your authorization URI.For a third-party OAuth provider, specify a scope from the set of scopes that the provider supports. For example, Login with Amazon supports `profile`, `profile:user_id`, and `postal_code`.
Domain List	An optional list of domains from which the authorization URI can retrieve data. If your login page retrieves content from other domains, enter those in this list.This field is only necessary for domains beyond your authorization URI. For example, suppose your authorization URI is `https://www.ridehailer.com/login`. If your page pulls in any content, such as images from domains other than `www.ridehailer.com`, add the domains to the Domain List. You can provide up to 30 domains.
Alexa Redirect URLs	The Amazon-provided redirection endpoints to which your login page must redirect the user after the user authenticates with your service. Alexa passes the value to use for a given request to your login page as the `redirect_uri` parameter included with the authorization URI. This field displays region-specific redirect URLs. For more details, see Alexa redirect URLs.

Step 2: Use access tokens in your skill

After you configure the implicit grant, add the logic to validate and use the access token in your skill code. Your skill can use the access token to retrieve user information from your resource server. For more details, see

Validate and Use Access Tokens in Custom Skill Code

Step 3: 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, update your skill code to check for the access token on incoming requests and take appropriate actions. Also, add code to send a link-account card in the response if the user didn’t enable or canceled account linking. When displayed in the Alexa app, this card displays a link to your authorization URI. The user can start the account linking process directly from this card.

Get Started

Plan and Implement

Reference

Implicit grant flow overview

Link the account

Use the access token in your skill

Authorization URI details

Alexa redirect URLs details

Access tokens

Prerequisites

Steps to configure an implicit grant

Step 1: Configure account linking

Account linking settings

Security provider information

Step 2: Use access tokens in your skill

Step 3: Test the account linking flow

​Implicit grant flow overview

​Link the account

​Use the access token in your skill

​Authorization URI details

​Alexa redirect URLs details

​Access tokens

​Prerequisites

​Steps to configure an implicit grant

​Step 1: Configure account linking

​Account linking settings

​Security provider information

​Step 2: Use access tokens in your skill

​Step 3: Test the account linking flow

​Related topics

Implicit grant flow overview

Link the account

Use the access token in your skill

Authorization URI details

Alexa redirect URLs details

Access tokens

Prerequisites

Steps to configure an implicit grant

Step 1: Configure account linking

Account linking settings

Security provider information

Step 2: Use access tokens in your skill

Step 3: Test the account linking flow

Related topics