In Ory, there are multiple ways to handle OAuth2 client logout, depending on your implementation needs: ## Browser-Based Logout For browser-based applications, you can use:

GET /oauth2/sessions/logout

This endpoint initiates and completes user logout at the Ory OAuth2 & OpenID provider and supports both Front-channel and Back-channel logout according to the OpenID Connect specifications [Ory API Reference](https://www.ory.sh/docs/reference/api). ## OpenID Connect Logout Options Ory supports three OpenID Connect logout mechanisms: 1. RP-Initiated Logout 2. Front-Channel Logout 3. Back-Channel Logout ### Front-Channel Logout If your OAuth2 client has registered a

frontchannel_logout_uri

, Ory will redirect the user's browser to that URL after logout. This allows your application to clear its own session data [OpenID Connect logout](https://www.ory.sh/docs/oauth2-oidc/oidc-logout). ### Back-Channel Logout For server-to-server logout communication, register a

backchannel_logout_uri

. Ory will send a POST request with a

logout_token

to this URL when the user logs out [OpenID Connect logout](https://www.ory.sh/docs/oauth2-oidc/oidc-logout). ## Post-Logout Redirection To redirect users after logout: 1. Register allowed URIs in your OAuth2 client's

post_logout_redirect_uris

field 2. Include the

post_logout_redirect_uri

parameter in your logout request 3. Optionally include

state

and

id_token_hint

parameters [OpenID Connect logout](https://www.ory.sh/docs/oauth2-oidc/oidc-logout#redirect-after-logout) ## Native App Logout For native applications, the SDK provides methods like:

javascript ory.frontend.performNativeLogout({   performNativeLogoutBody: {     session_token: '...'   } })

[SDK V1 upgrade guide](https://www.ory.sh/docs/guides/upgrade/sdk-v1#logout-for-native-apps) Remember that with OAuth2, logging out from the identity provider doesn't automatically log users out of connected applications, which is why these additional mechanisms are important for complete session management.

Yes, you can implement the OAuth2 logout by simply providing a link in your HTML that directs users to the logout endpoint. This is a common approach for browser-based applications. Here's how you can implement it:

html <a href="https://your-ory-project.projects.oryapis.com/oauth2/sessions/logout">Logout</a>

For a more complete implementation, you might want to include additional parameters:

html <a href="https://your-ory-project.projects.oryapis.com/oauth2/sessions/logout?post_logout_redirect_uri=https://your-app.com/logged-out&id_token_hint=YOUR_ID_TOKEN">Logout</a>

The

id_token_hint

parameter is recommended to include whenever possible. It helps identify which session to log out, especially in cases where: - The OAuth2 client has multiple sessions for the same user - The session cookie is no longer available - The login request was not remembered Including this parameter ensures proper logout even when the session cookie might not be available [OpenID Connect logout](https://www.ory.sh/docs/oauth2-oidc/oidc-logout#send-the-id-token-in-id_token_hint). When a user clicks this link, Ory will: 1. Process the logout request 2. Execute any configured front-channel or back-channel logout procedures 3. Redirect the user according to the configured post-logout redirect URI If you need more control over the logout process, you can also implement a custom logout endpoint using the Ory SDK as shown in the [Hydra Guides](https://www.ory.sh/docs/hydra/guides/logout).

The

id_token_hint

is a parameter used in OpenID Connect logout flows that contains an ID Token previously issued by the Authorization Server (Ory Hydra). It provides information about the user's current or past authenticated session with the client. ## Purpose of id_token_hint The

id_token_hint

serves several important functions: 1. Session Identification: It helps identify which user session should be terminated during logout, which is particularly useful when: - Multiple sessions exist for the same user - The session cookie is no longer available - The login request was not remembered (when "Remember Me" was not enabled) 2. Enabling Front/Back-Channel Logout: Even without an active session cookie, providing the

id_token_hint

allows Ory to execute Front-Channel and Back-Channel logout procedures for the specified client [OAuth2 logout debugging](https://www.ory.sh/docs/hydra/debug/logout). 3. Validation: The Authorization Server can verify that the user identified in the ID Token was previously authenticated, ensuring legitimate logout requests. ## Contents of id_token_hint The

id_token_hint

contains claims about the user's session, including: - Information about the end-user's current or past authenticated session - The

sid

(Session ID) claim that identifies the specific login session - The issuer claim that identifies which Authorization Server issued the token ## Usage in Logout Requests When implementing logout, you should include the

id_token_hint

in your logout request URL:

GET /oauth2/sessions/logout?id_token_hint=YOUR_ID_TOKEN&post_logout_redirect_uri=<https://your-app.com/logged-out>

It's recommended to always send this parameter when possible to ensure proper logout functionality [OpenID Connect logout](https://www.ory.sh/docs/oauth2-oidc/oidc-logout#send-the-id-token-in-id_token_hint). ## Important Considerations - In Hydra 2.x, there was a change in how the issuer claim is formatted (removal of trailing slash), which can cause logout failures for sessions created in older versions [Github Issue #3800](https://github.com/ory/hydra/discussions/3800) - When JWKs (JSON Web Keys) are rotated, there can be issues with validating the

id_token_hint

for existing sessions [Github Issue #3719](https://github.com/ory/hydra/issues/3719) Including the

id_token_hint

is a best practice for reliable logout functionality in OpenID Connect implementations.

When you call the

/oauth2/sessions/logout

endpoint in Ory, several important processes occur to properly terminate a user's session. Let me explain what happens behind the scenes: ## What Happens During Logout When the

/oauth2/sessions/logout

endpoint is called, Ory performs the following actions: 1. Authentication Session Invalidation: The endpoint invalidates the user's authentication session at the Ory OAuth2 & OpenID provider. This is the primary session that indicates the user is logged in to Ory itself [OpenID Connect Front- and Back-channel Enabled Logout](https://www.ory.sh/docs/hydra/reference/api). 2. Cookie Removal: When using Ory as the identity provider, the login provider will also invalidate the session cookie [Revokes OAuth 2.0 Login Sessions](https://www.ory.sh/docs/reference/api). 3. OpenID Connect Logout Procedures: The endpoint initiates both Front-channel and Back-channel logout procedures if configured: - Front-channel logout: Redirects the user's browser to the client's registered

frontchannel_logout_uri

- Back-channel logout: Sends a POST request with a

logout_token

to the client's registered

backchannel_logout_uri

These procedures are defined in the OpenID Connect specifications and allow connected applications to be notified about the logout [OpenID Connect logout](https://www.ory.sh/docs/oauth2-oidc/oidc-logout). ## What Is NOT Revoked It's important to understand that calling

/oauth2/sessions/logout

does not automatically revoke: 1. OAuth2 Access Tokens: The endpoint does not invalidate any OAuth2 access tokens that were previously issued. As stated in the documentation: "This endpoint does not invalidate any tokens" [Revokes OAuth 2.0 Login Sessions](https://www.ory.sh/docs/reference/api). 2. OAuth2 Refresh Tokens: Similarly, refresh tokens remain valid after this endpoint is called. ## How to Revoke Tokens If you need to revoke OAuth2 tokens, you should use separate endpoints: 1. For Access/Refresh Tokens: Use the

/oauth2/revoke

endpoint to invalidate specific tokens [Revoke OAuth 2.0 Access or Refresh Token](https://www.ory.sh/docs/hydra/reference/api). 2. For Consent Sessions: Use the

/admin/oauth2/auth/sessions/consent

endpoint to revoke a subject's consent sessions, which will also invalidate associated access tokens [Revoke OAuth 2.0 Consent Sessions](https://www.ory.sh/docs/reference/api). ## Session Layers in OAuth2 As noted in Auth0's documentation (cited by Ory), there are three separate logout mechanisms when using delegation protocols like OAuth2: - Application Session Layer - Auth0 (or in this case, Ory) Session Layer - Identity Provider Session Layer The

/oauth2/sessions/logout

endpoint primarily handles the Ory Session Layer logout [OAuth2 is Difficult in Some Use Cases](https://www.ory.sh/blog/oauth2-openid-connect-do-you-need-use-cases-examples). This separation of concerns is why logging out from the identity provider doesn't automatically log users out of all connected applications, which is a common source of confusion in OAuth2 implementations.

I understand you're having trouble with session invalidation when using the logout endpoint. Let's troubleshoot some common issues that might prevent proper session invalidation in Ory. ## Common Logout Issues There are several reasons why your session might not be properly invalidated when calling `/oauth2/sessions/logout`: 1. Missing or Invalid Session Cookie: The endpoint relies on a cookie named

oauth2_authentication_session

. Check if this cookie exists in your browser for the Ory domain [OAuth2 logout not working](https://www.ory.sh/docs/hydra/debug/logout). 2. "Remember Me" Not Enabled: If you didn't set

remember: true

when accepting the login request, the session might not persist properly [OAuth2 logout not working](https://www.ory.sh/docs/hydra/debug/logout). 3. Browser Privacy Settings: Some browsers with strict privacy policies (like Brave) can make it difficult for Ory to properly set and read cookies [OAuth2 logout not working](https://www.ory.sh/docs/hydra/debug/logout). 4. CSRF Issues: If you're experiencing 401 Unauthorized or 400 Bad Request responses, it could be related to CSRF protection [CSRF troubleshooting](https://www.ory.sh/docs/troubleshooting/csrf). 5. Multiple OAuth2 Flows: Running multiple OAuth2 flows simultaneously in the same browser can cause issues [CSRF troubleshooting](https://www.ory.sh/docs/troubleshooting/csrf#running-multiple-oauth2-flows-simultaneously). ## Recommended Solutions Try these approaches to resolve the issue: 1. Include

id_token_hint

: Always include the

id_token_hint

parameter in your logout request. This helps Ory identify which session to terminate even when cookies are unavailable [OpenID Connect logout](https://www.ory.sh/docs/oauth2-oidc/oidc-logout#send-the-id-token-in-id_token_hint). 2. Check Browser Network Tab: Use your browser's developer tools to inspect the network requests and responses when calling the logout endpoint. Look for any error messages or unexpected redirects. 3. Try Administrative Endpoints: If you need to forcibly invalidate sessions, you can use the administrative endpoint:

DELETE /admin/oauth2/auth/sessions/login

This endpoint allows you to revoke sessions by subject or session ID [Revokes OAuth2 Login Sessions](https://www.ory.sh/docs/reference/api). 4. Verify Session Status: You can check if your session was actually invalidated by attempting to access a protected resource or by using session management endpoints. 5. Ensure Proper Redirect Flow: Make sure you're not using AJAX to call

/oauth2/auth

as this isn't allowed with OAuth2 [CSRF troubleshooting](https://www.ory.sh/docs/troubleshooting/csrf#ory-oauth2). If you're still experiencing issues after trying these solutions, you might want to share more details about your specific implementation and the exact behavior you're observing.