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API Access Policies for Applications is currently available in Early Access. By using this feature, you agree to the applicable Free Trial terms in Okta’s Master Subscription Agreement.
In Auth0, you can control how applications access your APIs using application API access policies and client grants. A client grant provides fine-grained application access to an API. It associates:
  • An API identified by its audience or unique identifier.
  • An application identified by its client_id.
  • A list of permissions such as scopes and/or authorization_details_types that the application is allowed to request for the specified audience.
To learn more about the list of attributes you can define in a client grant, read Client grant attributes. To learn how to define and manage client grants, read Configure client grants.

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Application API access policies and client grants

When you configure an API’s application access policy to require_client_grant, only applications with a client grant defined can get an access token for the API. The client grant establishes the maximum permissions an application can request from the API by following the least privilege principle approach. As a result, Auth0 recommends using require_client_grant when configuring an API’s application access policy.

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Example: Social Media API

To illustrate how client grants follow the least privilege principle approach, say you have a Social Media API with the permissions: read:posts, write:posts, read:friends, and delete:posts. You create an application and define a client grant with the permissions: read:posts and write:posts. This client grant now serves as a hard ceiling. Even though the Social Media API has other permissions, your application can never request or be granted read:friends or delete:posts.

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User access vs. client access flows

In user access and client access flows, client grants define the final set of permissions that control an application’s access to an API. The client grant’s subject_type attribute determines the type of application access allowed for an API. An application can have up to two client grants for a single API:
  • When you set subject_type to client, you define its machine-to-machine permissions.
  • When you set subject_type to user, you define its permissions to act on the user’s behalf.
The following table explains how client grants control application access to APIs based on the access type flow:
Access typesubject_type attributeDescription
Client Credentials Flow (Machine-to-machine access flow)Set subject_type to client.The client grant directly authorizes the application to access the API on its own behalf instead of the end user’s behalf. The permissions you define in the client grant are the ones the application is authorized to receive in the access token.
User access flowsSet subject_type to user.The client grant defines the maximum permissions the application can request from the API. The final permissions in the access token issued to the application on the user’s behalf are the intersection of the permissions:

To learn more about user access flows, read Authentication and Authorization Flows. User access flows do not include the Client Credentials Flow.
You can modify the final scopes granted by the authorization server to the application or user using Actions.

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Client grant attributes

A client grant has several attributes that you can define to configure application access to APIs:
AttributeDescription
idUnique identifier of the client grant.
audienceUnique identifier of the API the client grant is for.
client_idThe unique ID of the application that is being granted access.
scopesAn array of strings representing the permissions the application can request.
authorization_details_typesAn array of strings representing rich authorization data types that the application can request. This attribute can only be specified for user access flows.
subject_typeThe type of application access the client grant allows for:
  • user: used for user access, which corresponds to all flows that generate a token associated with an end user.
  • client: used for machine access, which corresponds to the Client Credentials Flow.
organization_usageDetermines how the application may use organizations when accessing the API via the Client Credentials Flow. Possible values are: deny, allow, or require.

To learn more about the Organization settings, read Organizations for M2M Applications: Define Organization Behavior.
allow_any_organizationDetermines whether the application can access any organization when using the Client Credentials Flow.

To learn more about the Organization settings, read Organizations for M2M Applications: Define Organization Behavior.

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Configure client grants

You can use the Management API to configure client grants via the /client-grants endpoint.

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Create client grant

To create a new client grant, make a POST request to the /client-grants endpoint. The following code sample creates a client grant for an application to access the https://api.my-service.com API. The subject_type is user, which means the client grant is for user access, and allows the application to request the read:item scope and the payment authorization details type.

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Update client grant

To update an existing client grant, make a PATCH request to /client-grants/{id}. The following code sample updates an existing client grant to expand its permissions. The application can now also request the update:item scope and an additional credits_transfer authorization details type.

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Delete client grant

To delete a client grant, make a DELETE request to /client-grants/{id}. The following code sample removes the client grant which revokes the application’s access to the API:

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Retrieve client grants

You can also query and paginate through the client-grants collections by using parameters like client_id, audience, or subject_type. The following code sample retrieves all client grants that allow for user access to the https://api.my-service.com API.

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