Connect Tumblr first
- 01
Open Accounts in 1Post and choose Connect.
- 02
Pick Tumblr.
- 03
Sign in with Tumblr and approve access for the blog you want to post to.
- 04
Choose the blog in 1Post. It is ready to pick in the composer.
Then GET /v1/accounts returns the id of the Tumblr blog to use in the request.
Tumblr posts go into one of the account's blogs; GET /v1/accounts/{id}/targets lists them.
Send a post to Tumblr
curl https://api.get1post.com/v1/posts \
-H "Authorization: Bearer $ONEPOST_API_KEY" \
-H "Idempotency-Key: tumblr-first-post" \
-d '{"accounts":["ACCOUNT_ID"],"text":"A few photos from the studio this week.","schedule_at":"2026-11-02T15:00:00Z"}'The reply is 202 with the post (status scheduled) and one destination for Tumblr, which moves from queued to published or failed.
What you can send to Tumblr
- Text
- Up to 30 images
- One video
- Link
- Tags
What Tumblr publishes
- Tumblr allows 250 new published posts per day per user and 250 image uploads per day per user.
Tumblr rules the request is checked against
| Rule | What 1Post checks |
|---|---|
| Text limit | 4,096 characters, counted by code points |
| Media accepted | Images, GIFs, Video |
| Images per post | 30 |
| Videos per post | 1 |
| Threads | Yes, as a chain of replies |
| First comment | No |
| Posts per day, per connected account (1Post) | 50 |
The same table with sources is on the Tumblr specs page.
Tumblr options in the request
- Thread: send parts instead of text. Each part is one post in the chain, up to 100 parts, and each is counted on its own.
{
"accounts": [
"ACCOUNT_ID"
],
"parts": [
{
"text": "1/ The short version."
},
{
"text": "2/ The detail.",
"delay_min": 1
}
],
"use_next_free_slot": true
}Check the post before it is queued
Add "dry_run": true to test a post: nothing is kept, a valid one answers 200 and a broken one answers 422 naming the rule.
{
"error": {
"code": "invalid_for_platform",
"message": "tumblr refuses this post: Tumblr counts 4,128 of 4,096 characters in part 1. (text_too_long).",
"fix": "Fix the rule named in the message and send the post again.",
"retryable": false,
"request_id": "REQUEST_ID"
}
}An assistant connected to the MCP server sends the same fields to create_post; set one up.