Create a thread

Pass a parts array (1–25 items) to publish a thread. Each part has a caption and an optional media array (up to 4 items). Threads are supported on X and Mastodon; other platforms ignore parts.

The two platforms treat the top-level caption differently:

• X — when parts is present, the whole thread is built from parts: parts[0] is the first tweet and each later part replies to the previous one. Set caption to the same text as parts[0] (it's still required, and is what listings show). The top-level caption and media aren't posted, so put the first tweet's media on parts[0].media.
• Mastodon — caption (and media) is the first toot, and each part is posted as a reply under it.

The target account must be connected: creating a thread for a disconnected account is rejected up front with 400 (reconnect it first), rather than failing at publish time.

curl -X POST https://api.schedulin.app/v0/posts \
  -H "x-api-key: $SCHEDULIN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "socialAccountId": "acc_456",
    "caption": "We rebuilt our scheduler from scratch. Here is what we learned 🧵",
    "parts": [
      { "caption": "We rebuilt our scheduler from scratch. Here is what we learned 🧵" },
      { "caption": "1. Queues beat cron for anything user-facing." },
      {
        "caption": "2. Measure before you optimize. This chart surprised us:",
        "media": [{ "url": "https://www.schedulin.app/schedulin-analytics-card.png" }]
      }
    ],
    "action": "schedule",
    "scheduledAt": "2030-01-15T16:00:00Z"
  }'

const intro = "We rebuilt our scheduler from scratch. Here is what we learned 🧵";

await client.posts.create({
  socialAccountId: "acc_456",
  caption: intro,
  parts: [
    { caption: intro },
    { caption: "1. Queues beat cron for anything user-facing." },
    {
      caption: "2. Measure before you optimize. This chart surprised us:",
      media: [{ url: "https://www.schedulin.app/schedulin-analytics-card.png" }],
    },
  ],
  action: "schedule",
  scheduledAt: "2030-01-15T16:00:00Z",
});

from datetime import datetime, timezone

intro = "We rebuilt our scheduler from scratch. Here is what we learned 🧵"

client.posts.create(
    social_account_id="acc_456",
    caption=intro,
    parts=[
        {"caption": intro},
        {"caption": "1. Queues beat cron for anything user-facing."},
        {
            "caption": "2. Measure before you optimize. This chart surprised us:",
            "media": [{"url": "https://www.schedulin.app/schedulin-analytics-card.png"}],
        },
    ],
    action="schedule",
    scheduled_at=datetime(2030, 1, 15, 16, 0, tzinfo=timezone.utc),
)

Edit a thread

GET /v0/posts/{id} returns the thread as parts (in order, each with caption and media; empty for posts that aren't threads). To change it, send parts to PUT /v0/posts/{id} — it replaces the whole thread, and [] removes it (other platforms ignore parts, as on create). Part media takes the same items as the post's media (a URL or a media library { "id" }), so the parts from a GET can be sent back as-is. Published, publishing, and failed posts can't be edited (409).

On X, parts[0] stays in step with caption: sending parts without caption sets the caption to parts[0], and changing only caption also updates parts[0] when the two matched. Mastodon's caption is its own toot, so its parts change only when you send parts.

curl -X PUT https://api.schedulin.app/v0/posts/post_123 \
  -H "x-api-key: $SCHEDULIN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "parts": [
      { "caption": "We rebuilt our scheduler. Here is what we learned 🧵" },
      { "caption": "1. Queues beat cron for anything user-facing." }
    ]
  }'