Postfast

PostFast

Schedule social media posts across 9 platforms from one API. SaaS — no self-hosting needed.

Setup

1. Sign up at https://app.postfa.st/register
2. Go to Workspace Settings → generate an API key
3. Set the environment variable:

   export POSTFAST_API_KEY="your-api-key"
   

Base URL: https://api.postfa.st Auth header: pf-api-key: $POSTFAST_API_KEY

Core Workflow

1. List connected accounts

curl -s -H "pf-api-key: $POSTFAST_API_KEY" https://api.postfa.st/social-media/my-social-accounts

Returns array of { id, platform, platformUsername, displayName }. Save the id — it's the socialMediaId for posting.

2. Schedule a text post (no media)

curl -X POST https://api.postfa.st/social-posts \
  -H "pf-api-key: $POSTFAST_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "posts": [{
      "content": "Your post text here",
      "mediaItems": [],
      "scheduledAt": "2025-06-15T10:00:00.000Z",
      "socialMediaId": "ACCOUNT_ID_HERE"
    }],
    "controls": {}
  }'

3. Schedule a post with media (3-step flow)

Step A — Get signed upload URLs:

curl -X POST https://api.postfa.st/file/get-signed-upload-urls \
  -H "pf-api-key: $POSTFAST_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "contentType": "image/png", "count": 1 }'

Returns [{ "key": "image/uuid.png", "signedUrl": "https://..." }].

Step B — Upload file to S3:

curl -X PUT "SIGNED_URL_HERE" \
  -H "Content-Type: image/png" \
  --data-binary @/path/to/file.png

Step C — Create post with media key:

curl -X POST https://api.postfa.st/social-posts \
  -H "pf-api-key: $POSTFAST_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "posts": [{
      "content": "Post with image!",
      "mediaItems": [{ "key": "image/uuid.png", "type": "IMAGE", "sortOrder": 0 }],
      "scheduledAt": "2025-06-15T10:00:00.000Z",
      "socialMediaId": "ACCOUNT_ID_HERE"
    }],
    "controls": {}
  }'

For video: use contentType: "video/mp4", type: "VIDEO", key prefix video/.

4. List scheduled posts

curl -s -H "pf-api-key: $POSTFAST_API_KEY" https://api.postfa.st/social-posts

5. Delete a scheduled post

curl -X DELETE -H "pf-api-key: $POSTFAST_API_KEY" https://api.postfa.st/social-posts/POST_ID

6. Cross-post to multiple platforms

Include multiple entries in the posts array, each with a different socialMediaId. They share the same controls and mediaItems keys.

Platform-Specific Controls

Pass these in the controls object. See references/platform-controls.md for full details.

Helper Endpoints

• Pinterest boards: GET /social-media/{id}/pinterest-boards → returns [{ boardId, name }]
• YouTube playlists: GET /social-media/{id}/youtube-playlists → returns [{ playlistId, title }]

Rate Limits

• 60/min, 150/5min, 300/hour, 2000/day per API key
• Check X-RateLimit-Remaining-* headers
• 429 = rate limited, check Retry-After-* header

Media Specs Quick Reference

Tips for the Agent

• Always call my-social-accounts first to get valid socialMediaId values.
• For media posts, complete the full 3-step upload flow (signed URL → S3 PUT → create post).
• scheduledAt must be ISO 8601 UTC and in the future.
• Pinterest always requires pinterestBoardId — fetch boards first.
• LinkedIn documents use linkedinAttachmentKey instead of mediaItems.
• For carousels, include multiple items in mediaItems with sequential sortOrder.
• TikTok video thumbnails: set coverTimestamp (seconds) in mediaItems.