Mastodon's federated network means your audience can be spread across dozens of instances — Postclay connects to whichever instance your account actually lives on, so a Mastodon post schedules and publishes exactly like a post to any centralized platform.
Setup steps
- On your instance, go to Preferences → Development → New Application, and name it "Postclay".
- Under scopes, select at least read, write:statuses and write:media.
- Submit, open the application you just created, and copy "Your access token".
- In Postclay, enter your instance URL (e.g. https://mastodon.social) and the access token.
Limits & requirements
500 characters is the default limit on mastodon.social and most instances, though some instances raise this server-side — Postclay enforces the strict 500-character default so a post that fits on your instance never risks failing on a stricter one. Up to 4 images or one video can be attached per post.
What Postclay does differently for Mastodon
Because Mastodon has no single central platform, most schedulers either support one hardcoded instance or none at all. Postclay treats the instance URL as part of the connection itself, so you can connect accounts on multiple different Mastodon instances and schedule to all of them from the same calendar.
AI generation, tuned for Mastodon
Postclay's AI caption writer defaults to Mastodon's strict 500-character instance limit even though some instances allow more — a generated caption is guaranteed to publish on any Mastodon instance you might connect, not just the specific one you tested it on.
Troubleshooting
- My post was rejected by Mastodon even though it fit Postclay's counter.
- Postclay enforces the common 500-character default; if your instance actually allows more (or less), the effective limit may differ — check your instance's own settings under About → More.
- Postclay says the access token is invalid.
- Confirm the token has the read, write:statuses and write:media scopes — a token created without write:media can post text but will fail on any post with an image.
- I moved my account to a new instance.
- Reconnect with the new instance's URL and generate a fresh access token there — Postclay treats each instance as a separate connection, so the old one won't carry over.
Common questions
- What if I move to a different instance later?
- Reconnect with the new instance's URL and a fresh token — Postclay treats each instance as its own connection.
- Which scopes are actually required?
- read (to verify the token), write:statuses (to post) and write:media (to attach images or video).
- Does Postclay support Mastodon's content warnings (CW)?
- Not yet — posts publish without a content warning. If your community expects CWs for certain topics, add them manually after publishing for now.
- Can I schedule a poll to Mastodon through Postclay?
- Not currently — Postclay schedules text and media posts to Mastodon; native polls aren't part of the composer yet.