Your server sets the limit
The usual Mastodon limit is 500 characters, already more than a standard X post, and some servers raise it further. If a post is longer than that, Twinpost splits it into a short thread by default instead of cutting it off.
One nice detail: Mastodon counts every link as 23 characters, however long the address is. Posts with long links often fit more comfortably on Mastodon than you would expect.
What changes, side by side
| On X | On Mastodon | What Twinpost does |
|---|---|---|
| Long post | 500 characters by default, set per server | Splits it into a thread, by default |
| Images | Up to 4 images, with descriptions | Carries your images over, by default |
| Link preview | Generated by your server from the page | Your server decides how the preview looks |
| Replies, reposts, quote posts | n/a | Not mirrored by default; they stay on X |
Set it up
- Create a Twinpost account and connect X.
- Choose Mastodon and type your server's address, for example
mastodon.socialorfosstodon.org. - Your server opens and asks whether to let Twinpost post for you. Approve it.
- Start mirroring. The activity page links to each copy on your server.
Mastodon is rolling out in the app now; if it shows “coming soon” there, it is not switched on for your account yet. You can remove Twinpost at any time from your server's settings under authorized apps, or disconnect it from the connect page.
Questions about Mastodon
Does it work with my server, not just mastodon.social?
You type in your server's address when you connect, so any server running Mastodon that allows third-party apps should work. Some servers restrict automated posting in their rules; it is worth reading yours.
Will it post as a bot?
No. Posts go out from your own account, the same one you read and reply with. If your server asks for automated accounts to be marked, you can tick the bot flag in your Mastodon profile settings yourself.
Can it add a content warning?
Not at the moment. Twinpost mirrors what you wrote on X, and X has no equivalent. If a post needs a content warning on Mastodon, post that one by hand.
What about people I mention on X?
On Mastodon a bare @name points to someone on your own server, who may not be the person you meant on X. If it matters that someone is tagged, reply to the mirrored post and use their full @name@server address.