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Integrate with Matrix Synapse

Support level: Community

What is Matrix Synapse?​

Synapse is an open source Matrix homeserver implementation, written and maintained by Element. Matrix is the open standard for secure and interoperable real-time communications.

-- https://github.com/element-hq/synapse

Preparation​

The following placeholders are used in this guide:

  • matrix.company is the public FQDN where Matrix clients reach Synapse.
  • authentik.company is the FQDN of the authentik installation.
info

This documentation lists only the settings that you need to change from their default values. Be aware that any changes other than those explicitly mentioned in this guide could cause issues accessing your application.

authentik configuration​

Redirect URI changes in authentik 2026.5

In authentik versions earlier than 2026.5, all Redirect URIs are automatically treated as Authorization type. If you are using one of these older authentik versions, add only the Authorization URL to your Redirect URIs and do not configure a Post Logout URI.

To support the integration of Matrix Synapse with authentik, you need to create an application/provider pair in authentik.

Create an application and provider​

  1. Log in to authentik as an administrator and open the authentik Admin interface.

  2. Navigate to Applications > Applications and click New Application to open the application wizard.

    • Application: provide a descriptive name, an optional group for the type of application, the policy engine mode, and optional UI settings. Take note of the Slug as it will be required later.
    • Choose a Provider type: select OAuth2/OpenID Connect as the provider type.
    • Configure the Provider: provide a name (or accept the auto-provided name), the authorization flow to use for this provider, and the following required configurations.
      • Note the Client ID and Client Secret values because they will be required later.
      • Add a Redirect URI of type Strict Authorization as https://matrix.company/_synapse/client/oidc/callback.
      • Select any available RSA-based Signing Key. Matrix Synapse does not support ECC keys for authentik.
      • Leave Encryption Key empty.
    • Configure Bindings (optional): you can create a binding (policy, group, or user) to manage the listing and access to applications on a user's Application Dashboard page.

  3. Click Submit to save the new application and provider.

Matrix Synapse configuration​

Synapse's Docker images and Debian packages include the OIDC dependencies. If you installed Synapse in a virtual environment, install the OIDC extras before enabling this configuration:

/path/to/env/bin/pip install matrix-synapse[oidc]

Add the following configuration to your Synapse configuration file:

homeserver.yaml
oidc_providers:
    - idp_id: authentik
      idp_name: authentik
      discover: true
      issuer: "https://authentik.company/application/o/<application_slug>/"
      client_id: "<Client ID from authentik>"
      client_secret: "<Client Secret from authentik>"
      scopes:
          - "openid"
          - "profile"
          - "email"
      user_mapping_provider:
          config:
              localpart_template: "{{ user.preferred_username }}"
              display_name_template: "{{ user.preferred_username|capitalize }}"

jwt_config:
    enabled: true
    secret: "<Client Secret from authentik>"
    algorithm: "RS256"

The display_name_template line can use {{ user.name|capitalize }} if your authentik users have names and you want Synapse display names to use those values.

Restart Synapse to apply the configuration.

Configuration verification​

To confirm that authentik is properly configured with Matrix Synapse, open your Matrix client, choose your Synapse homeserver, and sign in with authentik. You should be redirected to authentik for authentication and then redirected back to your Matrix client.

Resources​