Title: Mastodon publishing support - OpenPost Description: See how OpenPost handles Mastodon formats, setup needs, limits, and live-test notes. Canonical: https://openpo.st/platforms/mastodon Source: [https://openpo.st/platforms/mastodon](https://openpo.st/platforms/mastodon) [All platforms](https://openpo.st/platforms) Mastodon OAuth 2.0 per instance # Publish to the Mastodon server your community already uses. Connect a public Mastodon server, then schedule posts, media, links, and reply threads. This page is for people deciding whether OpenPost fits their Mastodon publishing workflow. **Implemented:** Publishing is implemented **Hosted service certification:** No Hosted service provider-format certification claim is current. [Platform guide](https://docs.openpo.st/providers/mastodon) Formats and limits ## Different formats, different rules. OpenPost checks the text and media rules for the format you choose. | Format | Text | Media | | --- | --- | --- | | Post, thread, or link | 500 characters by default | Text only | | Media post | 500 characters by default | Up to 4 images, GIFs, or MP4 attachments | ### Provider limits and scope - 500 characters by default - Up to 4 attachments - Reply threads and OpenPost scheduling - Instance rules can override the defaults Connect and test ## Set up Mastodon in three checks. 1. Choose Mastodon in Social accounts and enter the public server address. 1. Approve the dynamically registered or operator-configured app on that server. 1. Confirm the instance-specific text and media rules before scheduling. Known limits ## What can still block a post. - Character, attachment, and video limits can differ by server. - Custom instances must be public HTTPS and allow app registration. - One adapter registration is maintained per Mastodon instance. **Account requirement:** An account on a public HTTPS Mastodon instance that allows app access. **Verification:** Check the server rules and publish one media test before you rely on a new server. ## Use the current callback address, permissions, and media setup. Social network developer pages change. The OpenPost guide lists the settings and checks you need now. [Read the Mastodon guide](https://docs.openpo.st/providers/mastodon)