Mastodon: posting rules and settings
What a Mastodon channel accepts in Posty: media, limits, required fields, and the fields of the settings object for the API.
Basics
mastodon-custom, mastodonPost types
The same channel accepts more than one kind of post, and each kind has different requirements. The table shows what you need for each.
| Type | Media | Notes |
|---|---|---|
| Text | none | No extra notes. |
| Image | images | No extra notes. |
| Video | 1 video | No extra notes. |
| Thread | each part has its own | The remaining items in the value array go out as replies to the first, in order. |
Rules
- Mastodon has no platform-specific settings. The __type field is enough in the settings object.
- You connect an account on any Mastodon server. You type the address of the server, Posty registers itself there, and you sign in as usual.
- Use mastodon-custom as the __type for an account on any server, and mastodon for an account connected with the mastodon.social option.
- Posty counts 500 characters, the Mastodon default, even where a server allows more.
- You write a thread as extra parts of the post. They go out as replies to it, in order.
Settings fields
The settings object only needs the __type field. The editor does not show a separate settings section for this channel.
Examples
Each example is one item in the POST /public/v1/posts request's posts array. The envelope around it is always this:
{
"type": "schedule",
"date": "2026-09-15T09:00:00.000Z",
"shortLink": false,
"posts": [ /* the item below */ ]
}Text post
The settings object only needs the __type field: mastodon-custom, or mastodon for a channel connected with the mastodon.social option.
{
"integration": { "id": "<mastodon-channel>" },
"value": [{ "content": "<p>Hello, fediverse!</p>", "image": [] }],
"settings": { "__type": "mastodon-custom" }
}Thread
{
"integration": { "id": "<mastodon-channel>" },
"value": [
{ "content": "<p>Part one.</p>", "image": [] },
{ "content": "<p>Part two.</p>", "image": [], "delay": 1 }
],
"settings": { "__type": "mastodon-custom" }
}The channel ID comes from the channel list, and the path values for images and videos from media upload. The exact schema for the connected account comes from the settings schema endpoint. From the command line, the same thing is the --settings flag. See the CLI examples.