Title: Mastodon Description: Connect an account on a Mastodon server, with optional fixed app credentials. Canonical: https://docs.openpo.st/self-hosting/integrations/mastodon Source: [https://docs.openpo.st/self-hosting/integrations/mastodon](https://docs.openpo.st/self-hosting/integrations/mastodon) # Mastodon Mastodon accounts belong to individual servers. OpenPost can register an app when someone connects to a public HTTPS server. You can also configure a fixed app for a server your team uses. ## Connect a public server 1. In OpenPost, choose your workspace and open **Settings → Workspace → Social accounts → Mastodon**. 2. Select **Continue to Mastodon**, then enter the address of the server that hosts your account, such as `https://mastodon.social`. Do not enter your profile URL. 3. Continue to the server's authorization page and approve OpenPost. 4. By default, Mastodon shows an authorization code. Copy it and return to OpenPost. In the Mastodon connection dialog, select **Code**, paste it into **Authorization code**, and select **Connect account**. 5. Publish a short test post and open the resulting link from its publication details. OpenPost registers the app on that server through `POST /api/v1/apps` with `read write` scopes and keeps the client secret encrypted. The default redirect is `urn:ietf:wg:oauth:2.0:oob`, which makes Mastodon display a code instead of redirecting to a callback. See Mastodon's [app registration](https://docs.joinmastodon.org/methods/apps/) and [authorization](https://docs.joinmastodon.org/methods/oauth/) documentation.  Mastodon server address in OpenPost. Screenshot uses example values. ## Configure a fixed server app Use this path if you want to preconfigure a known server or its app registration endpoint is unavailable to OpenPost. 1. On that Mastodon server, open **Preferences → Development → New application**. Name the app `OpenPost`, add `read` and `write` permissions, and register `urn:ietf:wg:oauth:2.0:oob` as the redirect URI. Save the app and copy its client ID and secret. Server menus can differ. 2. Add the server and credentials to `MASTODON_SERVERS` in your server environment. Keep the JSON on one line in `.env`: ```dotenv MASTODON_SERVERS=[{"name":"Team server","client_id":"your-client-id","client_secret":"your-client-secret","instance_url":"https://social.example"}] ``` 3. Recreate OpenPost with `docker compose up -d --force-recreate openpost` to load the changed environment. The server should appear as a choice when connecting Mastodon. You can instead save a Mastodon app in [Instance → Configuration → Provider apps](https://docs.openpo.st/self-hosting/integrations#save-your-provider-credentials). If you change `MASTODON_REDIRECT_URI`, register that exact URI on the Mastodon app too. The default out-of-band flow needs no public callback. ## If the connection fails - Enter the server origin, for example `https://social.example`, without a username or path. OpenPost accepts public HTTPS instances. - If app registration fails, ask the server administrator whether it accepts new OAuth apps, or configure a fixed app for that server. - If Mastodon rejects the authorization code, start the connection again and copy the new code. Check that the app's registered redirect URI matches `MASTODON_REDIRECT_URI`. - If a fixed server is missing, check the `MASTODON_SERVERS` JSON and the container logs after restart.