See every channel and its status on Channels. Step-by-step help is in the Mastodon guide.

Connect your Mastodon account

Mastodon has no central service: every account lives on a server of its own. On the Channels screen, choose Mastodon. The server box already says mastodon.social; if your account is elsewhere, type its address, or paste your handle such as @alice@example.social. OmniPosts sends you to your server to sign in and approve it, and you come back to OmniPosts. You sign in on Mastodon's own page; OmniPosts never sees your email or password.

OmniPosts asks for permission to read your account, read your posts, write posts and upload media. The read permissions are used to check that a post went out and to read its numbers. Mastodon sign-ins do not expire: they stay valid until you revoke OmniPosts on your server.

What you can post to Mastodon

• Text up to 500 characters on a standard server. Mastodon counts every link as 23 characters, and a mention of someone on another server as just the username.
• Up to 4 images per post, JPEG, PNG, GIF or WebP, up to 16 MB each, with alt text of up to 1500 characters.
• Your server's own limits. Servers can change these numbers. OmniPosts reads your server's limits when you connect and applies them before sending, so a post your server would refuse is caught in the composer.
• Visibility: public, unlisted, or followers only.
• Threads through the API: a chain of replies to your own post.
• Video is not supported yet.

Every post goes out once

OmniPosts sends an idempotency key with each post, which Mastodon honours for about an hour. After that, OmniPosts checks your recent posts before it would ever try again, and a post whose fate is unknown is never sent a second time on its own. OmniPosts also checks your server's address before every call: if it stops resolving the post is retried later, and if it points at a private network nothing is sent.

The result for your Mastodon channel is one of: posted, with a link; failed, with the reason and one thing to do about it; or still being checked.

Numbers your server shares

Mastodon shares favourites, boosts, replies and quotes for each post (quotes need Mastodon 4.5 or newer), and followers, following and post count for the account. The counts are your server's view of the post, not a network-wide total. Views, reach and impressions are not shared, so OmniPosts shows them as "Not available" with the reason. See Honest numbers.

Post to Mastodon from your code

Everything above works through the HTTP API, with idempotency keys and signed webhooks. GET /v1/providers returns Mastodon's standard limits and settings as data. Rate limits are set by your server's admin; a standard server allows 300 requests per 5 minutes per account.

Questions

Can I schedule Mastodon posts?

Yes. Post now, pick a date and time, or add the post to your queue and it takes your next free posting time. Posts go out from our servers, so your computer can be off.

Does it work with my Mastodon server?

Very likely. OmniPosts works with any Mastodon server, and servers that speak the same API, as long as it is reachable over https on a public address. It registers itself with your server when you connect, so your admin does not have to do anything.

Does OmniPosts see my Mastodon password?

No. You sign in on your server's own page and approve OmniPosts there. You can revoke that access from your server's settings at any time.

Can I post to Mastodon and my other channels at the same time?

Yes, to every channel you have connected that is open today: Bluesky, Mastodon and Telegram. Pick them in the composer. Each gets its own preview and its own limit check, and you can change the text for one without touching the others.

Can I choose who sees a post?

Yes. The composer has a Mastodon visibility setting: public (the default), unlisted, or followers only.