PostFast
Schedule social media posts across 11 platforms from one API. SaaS — no self-hosting needed.
Setup
- Sign up at https://app.postfa.st/register (7-day free trial, no credit card)
- Go to Workspace Settings → generate an API key
- 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
Important: The header name is pf-api-key (not Authorization: Bearer or x-api-key). Regenerating your key in settings permanently invalidates the previous one. See Troubleshooting if you get 403 errors.
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 required for every post.
Platform values: TIKTOK, INSTAGRAM, FACEBOOK, X, YOUTUBE, LINKEDIN, THREADS, BLUESKY, PINTEREST, TELEGRAM, GOOGLE_BUSINESS_PROFILE
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": "2026-06-15T10:00:00.000Z",
"socialMediaId": "ACCOUNT_ID_HERE"
}],
"controls": {}
}'
Returns { "postIds": ["uuid-1"] }.
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": "2026-06-15T10:00:00.000Z",
"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?page=0&limit=20"
Returns { "data": [...], "totalCount": 25, "pageInfo": { "page": 1, "hasNextPage": true, "perPage": 20 } }.
Query parameters:
page (int, default 0) — 0-based page index. Response shows 1-based display page in pageInfo.pagelimit (int, default 20, max 50) — items per pageplatforms (string) — comma-separated filter: FACEBOOK,INSTAGRAM,Xstatuses (string) — comma-separated: DRAFT, SCHEDULED, PUBLISHED, FAILEDfrom / to (ISO 8601 UTC) — date range filter on scheduledAt
Example: GET /social-posts?page=0&limit=50&platforms=X,LINKEDIN&statuses=SCHEDULED&from=2026-06-01T00:00:00Z&to=2026-06-30T23:59:59Z
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.
7. Generate a connect link (for clients)
Let clients connect their social accounts to your workspace without creating a PostFast account:
curl -X POST https://api.postfa.st/social-media/connect-link \
-H "pf-api-key: $POSTFAST_API_KEY" \
-H "Content-Type: application/json" \
-d '{ "expiryDays": 7, "sendEmail": true, "email": "client@example.com" }'
Returns { "connectUrl": "https://app.postfa.st/connect?token=..." }. Share the URL — they can connect accounts directly. Rate limit: 50/hour.
8. Create a draft post
Omit scheduledAt and set status: "DRAFT" to save without scheduling:
curl -X POST https://api.postfa.st/social-posts \
-H "pf-api-key: $POSTFAST_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"posts": [{ "content": "Draft idea...", "mediaItems": [], "socialMediaId": "ACCOUNT_ID" }],
"status": "DRAFT",
"controls": {}
}'
9. Get post analytics
Fetch published posts with their performance metrics:
curl -s -H "pf-api-key: $POSTFAST_API_KEY" \
"https://api.postfa.st/social-posts/analytics?startDate=2026-03-01T00:00:00.000Z&endDate=2026-03-31T23:59:59.999Z&platforms=TIKTOK,INSTAGRAM"
Query parameters:
startDate (ISO 8601, required) — start of date rangeendDate (ISO 8601, required) — end of date rangeplatforms (string, optional) — comma-separated filtersocialMediaIds (string, optional) — comma-separated account UUIDs
Returns { "data": [{ id, content, socialMediaId, platformPostId, publishedAt, latestMetric }] }.
latestMetric fields: impressions, reach, likes, comments, shares, totalInteractions, fetchedAt, extras. All numbers are strings (bigint). latestMetric is null if metrics haven't been fetched yet.
Supported platforms for analytics: Facebook, Instagram, Threads, LinkedIn, TikTok, YouTube, Pinterest. LinkedIn personal accounts are excluded. YouTube returns views, likes, comments, and total interactions (no reach or shares).
Pinterest specifics (requires a Pinterest business account):
Canonical fields:
impressions, likes (reactions: heart/applaud/idea/etc.), comments — lifetime totals from Pinterest's pin endpoint.shares — 90-day rolling save count. This is the only canonical field that isn't lifetime; Pinterest's v5 API does not expose lifetime save totals.totalInteractions — sum of pin clicks + outbound clicks + saves + reactions + comments. Mostly lifetime, but the saves portion is 90-day, so treat it as a "best available" interaction total rather than strictly lifetime.reach — always null (Pinterest doesn't return it).
extras (lifetime):
pin_clicks — opens of the pin's close-up viewoutbound_clicks — clicks to the destination URLengagement, engagement_rate, pin_click_rate, outbound_click_rate — Pinterest's lifetime analytics fields, passed through when present
extras (90-day rolling):
impressions_90d, pin_clicks_90d, outbound_clicks_90d — same metrics as their lifetime counterparts but for the last 90 dayssave_rate — saves ÷ impressions over the 90-day window
extras for video pins (when present):
video_mrc_views, video_avg_watch_time, video_v50_watch_time, video_10s_views, video_start, quartile_95_percent_view
Refresh cadence: every 6 hours for pins under 14 days old, once a day for pins 14–60 days old. You can also trigger a manual refresh from the dashboard.
Rate limit: 350/hour.
Common Patterns
Pattern 1: Cross-platform campaign
Post the same content to LinkedIn, X, and Threads at the same time:
curl -X POST https://api.postfa.st/social-posts \
-H "pf-api-key: $POSTFAST_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"posts": [
{ "content": "Big announcement!", "mediaItems": [], "scheduledAt": "2026-06-15T09:00:00.000Z", "socialMediaId": "LINKEDIN_ID" },
{ "content": "Big announcement!", "mediaItems": [], "scheduledAt": "2026-06-15T09:00:00.000Z", "socialMediaId": "X_ID" },
{ "content": "Big announcement!", "mediaItems": [], "scheduledAt": "2026-06-15T09:00:00.000Z", "socialMediaId": "THREADS_ID" }
],
"controls": {}
}'
See examples/cross-platform-post.json for a complete example.
Pattern 2: Instagram Reel with upload
- Get signed URL with
contentType: "video/mp4"
- PUT video to signed URL
- Create post with
instagramPublishType: "REEL"
Optional: add a custom cover image by uploading a JPEG (max 8MB) via the same 3-step flow, then set coverImageKey in the media item. You can also set coverTimestamp (milliseconds) as a fallback frame.
See examples/instagram-reel.json for the basic request, or examples/instagram-reel-cover.json for a Reel with a custom cover image.
Pattern 3: TikTok video with privacy settings
Upload video, then post with privacy controls:
{
"tiktokPrivacy": "PUBLIC",
"tiktokAllowComments": true,
"tiktokAllowDuet": false,
"tiktokAllowStitch": false,
"tiktokBrandContent": true
}
See examples/tiktok-video.json.
Pattern 4: Pinterest pin (board required)
Always fetch boards first, then post:
curl -s -H "pf-api-key: $POSTFAST_API_KEY" \
https://api.postfa.st/social-media/PINTEREST_ACCOUNT_ID/pinterest-boards
See examples/pinterest-pin.json.
Pattern 5: YouTube Short with tags and playlist
Upload video, then post with YouTube controls:
{
"youtubeIsShort": true,
"youtubeTitle": "Quick Tip: Batch Your Content",
"youtubePrivacy": "PUBLIC",
"youtubePlaylistId": "PLxxxxxx",
"youtubeTags": ["tips", "productivity", "social media"],
"youtubeMadeForKids": false
}
See examples/youtube-short.json.
Pattern 5b: YouTube video with custom thumbnail
Upload both video and thumbnail image, then reference the thumbnail key in controls:
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/jpeg", "count": 1 }'
{
"youtubeIsShort": false,
"youtubeTitle": "Full Tutorial: Social Media Strategy",
"youtubePrivacy": "PUBLIC",
"youtubeThumbnailKey": "image/abc123.jpg",
"youtubeTags": ["tutorial", "social media"],
"youtubeMadeForKids": false
}
Thumbnail specs: JPEG/PNG recommended, max 2MB, 1280x720 (16:9), min width 640px. Requires phone-verified YouTube channel. If thumbnail upload fails, the video still publishes without the custom thumbnail.
See examples/youtube-video-thumbnail.json.
Pattern 6: Google Business Profile post
Always fetch locations first, then post with GBP-specific controls:
curl -s -H "pf-api-key: $POSTFAST_API_KEY" \
https://api.postfa.st/social-media/GBP_ACCOUNT_ID/gbp-locations
Three post types: STANDARD (updates), EVENT (time-bound), OFFER (deals with coupons). EVENT and OFFER require gbpEventTitle, gbpEventStartDate, gbpEventEndDate.
See examples/gbp-standard.json, examples/gbp-event.json, and examples/gbp-offer.json.
Pattern 7: LinkedIn document post
Documents (PDF, PPTX, DOCX) display as swipeable carousels on LinkedIn.
- Get signed URL with
contentType: "application/pdf"
- PUT the file to signed URL
- Create post using
linkedinAttachmentKey instead of mediaItems
See examples/linkedin-document.json.
Pattern 8: First comment (auto-posted after publish)
Add a firstComment to any post — it's auto-posted ~10 seconds after the main post goes live (up to 3 retries):
{
"posts": [{ "content": "Main post text", "firstComment": "Link: https://postfa.st", "mediaItems": [], "scheduledAt": "...", "socialMediaId": "X_ID" }],
"controls": {}
}
Supported on: X, Instagram, Facebook, YouTube, Threads. NOT supported on: TikTok, Pinterest, Bluesky, LinkedIn.
See examples/x-first-comment.json.
Pattern 9: X (Twitter) retweet
Schedule a retweet — content and media are ignored:
{
"posts": [{ "content": "", "scheduledAt": "...", "socialMediaId": "X_ID" }],
"controls": { "xRetweetUrl": "https://x.com/username/status/1234567890" }
}
See examples/x-retweet.json.
Pattern 10: Batch scheduling (a week of posts)
Schedule multiple posts at different times in a single API call (up to 15 posts per request):
See examples/batch-scheduling.json.
Platform-Specific Controls
Pass these in the controls object. See references/platform-controls.md for full details.
| Platform | Key Controls |
|---|
| TikTok | tiktokPrivacy, tiktokAllowComments, tiktokAllowDuet, tiktokAllowStitch, tiktokIsDraft, tiktokIsAigc, tiktokBrandOrganic, tiktokBrandContent, tiktokAutoAddMusic |
| Instagram | instagramPublishType (TIMELINE/STORY/REEL), instagramPostToGrid, instagramCollaborators, instagramTrialReelStrategy |
| Facebook | facebookContentType (POST/REEL/STORY), facebookReelsCollaborators |
| YouTube | youtubeIsShort, youtubeTitle, youtubePrivacy, youtubePlaylistId, youtubeTags, youtubeMadeForKids, youtubeCategoryId, youtubeThumbnailKey |
| LinkedIn | linkedinAttachmentKey, linkedinAttachmentTitle (for document posts) |
| X (Twitter) | xRetweetUrl (retweet) |
| Pinterest | pinterestBoardId (required), pinterestLink |
| Google Business Profile | gbpLocationId (required), gbpTopicType, gbpCallToActionType, gbpCallToActionUrl, gbpEventTitle, gbpEventStartDate, gbpEventEndDate, gbpOfferCouponCode, gbpOfferRedeemUrl, gbpOfferTerms |
| Bluesky | No platform-specific controls — text + images only |
| Threads | No platform-specific controls — text + images/video |
Helper Endpoints
- Pinterest boards:
GET /social-media/{id}/pinterest-boards → returns [{ boardId, name }]
- YouTube playlists:
GET /social-media/{id}/youtube-playlists → returns [{ playlistId, title }]
- GBP locations:
GET /social-media/{id}/gbp-locations → returns [{ id, locationId, title, address, mapsUri }]. Use locationId as gbpLocationId in controls
- Connect link:
POST /social-media/connect-link → returns { connectUrl }. Let clients connect accounts without a PostFast account. Params: expiryDays (1-30, default 7), sendEmail (bool), email (required if sendEmail=true)
Rate Limits
Global (per API key): 60/min, 150/5min, 300/hour, 2000/day
Per-endpoint:
POST /social-posts: 350/dayGET /social-posts: 200/hourGET /social-posts/analytics: 350/hourPOST /social-media/connect-link: 50/hour
Platform limits:
- X (Twitter) via API: 5 posts per account per day — do not exceed this
Check X-RateLimit-Remaining-* headers. 429 = rate limited, check Retry-After-* header. For batch operations, add a 1-second delay between API calls.
Media Specs Quick Reference
| Platform | Images | Video | Carousel |
|---|
| TikTok | Carousels only | ≤250MB, MP4/MOV, 3s-10min | 2-35 images |
| Instagram | JPEG/PNG | ≤1GB, 3-90s (Reels) | Up to 10 |
| Facebook | ≤30MB, JPG/PNG | 1 per post | Up to 10 images |
| YouTube | — | Shorts ≤3min, H.264 | — |
| LinkedIn | Up to 9 | ≤10min | Up to 9, or documents (PDF/PPTX/DOCX) |
| X (Twitter) | Up to 4 | — | — |
| Pinterest | 2:3 ratio ideal | Supported | 2-5 images |
| Google Business Profile | 1 image (JPEG/PNG, 5MB max) | Not supported | — |
| Bluesky | Up to 4 | Not supported | — |
| Threads | Supported | Supported | Up to 10 |
| Telegram | Up to 10 | Supported | Up to 10 mixed media |
Common Gotchas
- Always fetch accounts first —
socialMediaId is a UUID, not a platform name. Call GET /social-media/my-social-accounts to get valid IDs.
- Media MUST go through 3-step upload — No external URLs. Always: get signed URL → PUT to S3 → use the
key in mediaItems.
scheduledAt must be in the future — ISO 8601 UTC format. Past dates return 400.- Pinterest ALWAYS requires
pinterestBoardId — Fetch boards first with GET /social-media/{id}/pinterest-boards.
- TikTok requires video for standard posts — Images only work in carousels (2-35 images).
- LinkedIn documents use
linkedinAttachmentKey — NOT mediaItems. Set mediaItems: [] when posting documents.
- Content-Type on S3 PUT must match — The
Content-Type header in your S3 PUT must match what you requested in get-signed-upload-urls.
- Instagram Reels need video 3-90 seconds — Outside this range returns an error.
- YouTube Shorts need video under 3 minutes — H.264 codec with AAC audio recommended.
- X (Twitter) has a 280 character limit — Longer content is silently truncated.
- Cross-posting shares controls — The
controls object applies to ALL posts in the batch. Platform-irrelevant controls are ignored.
- X (Twitter) API limit is 5 posts/account/day — Exceeding this risks account restrictions.
firstComment only works on 5 platforms — X, Instagram, Facebook, YouTube, Threads. TikTok, Pinterest, Bluesky, LinkedIn return a validation error.- Retweets ignore content/media — When
xRetweetUrl is set, the content and mediaItems fields are ignored.
- LinkedIn documents support PDF, DOC, DOCX, PPT, PPTX — Max 60MB. Cannot mix with regular media.
- Pagination is 0-based —
page=0 returns the first page. Response pageInfo.page shows 1-based display number.
- Instagram trial reels require — Setting without it returns 400. Also cannot be combined with .
Troubleshooting
403 "Missing organizationId or activeWorkspaceId"
This is the most common error. It means the API didn't recognize your key. Check these in order:
-
Wrong header name. The header must be exactly pf-api-key. Not Authorization: Bearer, not x-api-key, not api-key. Example:
curl -H "pf-api-key: YOUR_KEY_HERE" https://api.postfa.st/social-media/my-social-accounts
curl -H "Authorization: Bearer YOUR_KEY_HERE" ...
curl -H "x-api-key: YOUR_KEY_HERE" ...
-
Env var not set. If $POSTFAST_API_KEY isn't set in your shell, the literal string $POSTFAST_API_KEY gets sent as the key value. Verify it's set:
echo $POSTFAST_API_KEY
If empty, re-export it. If you're using a .env file, make sure your tool actually loads it (dotenv, direnv, etc.). Shell quoting matters: use double quotes around the value if it contains special characters.
-
Regenerated key. Each time you click "Generate API Key" in PostFast settings, the previous key is permanently invalidated. Only regenerate if the old key is compromised. If you regenerated and are still using the old key, that's why it fails.
-
Wrong key entirely. Your PostFast API key is a 44-character base64 string ending with =. Don't confuse it with keys from other services (OpenAI sk-proj-..., Stripe sk_live_..., etc.).
401 Invalid or missing API key
The pf-api-key header is either missing from the request or the value is empty. Double-check that your HTTP client is actually sending the header (some tools strip custom headers on redirects).
429 Rate limit exceeded
You've hit the per-workspace rate limit. Check the Retry-After-Minute, Retry-After-5Minutes, Retry-After-Hour, or Retry-After-Day response header for when you can retry. Limits: 60/min, 150/5min, 300/hour, 2,000/day.
Supporting Resources
Reference docs:
Ready-to-use examples:
Quick Reference
# Auth
Header: pf-api-key: $POSTFAST_API_KEY
# List accounts
GET /social-media/my-social-accounts
# Schedule post
POST /social-posts { posts: [{ content, mediaItems, scheduledAt, socialMediaId, firstComment? }], status?, approvalStatus?, controls: {} }
# Draft post (no scheduledAt needed)
POST /social-posts { posts: [...], status: "DRAFT", controls: {} }
# List posts (page is 0-based, limit max 50)
GET /social-posts?page=0&limit=20
GET /social-posts?page=0&limit=50&platforms=X,LINKEDIN&statuses=SCHEDULED&from=2026-06-01T00:00:00Z&to=2026-06-30T23:59:59Z
# Delete post
DELETE /social-posts/:id
# Upload media (3 steps)
POST /file/get-signed-upload-urls { contentType, count }
PUT <signedUrl> (raw file, matching Content-Type)
# then use key in mediaItems
# Pinterest boards
GET /social-media/:id/pinterest-boards
# YouTube playlists
GET /social-media/:id/youtube-playlists
# GBP locations
GET /social-media/:id/gbp-locations
# Post analytics (published posts with metrics)
GET /social-posts/analytics?startDate=...&endDate=...&platforms=...
# Connect link (for clients)
POST /social-media/connect-link { expiryDays?, sendEmail?, email? }
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.
- Video cover images: use
coverImageKey in mediaItems for IG Reels, FB Reels, Pinterest video. Use coverTimestamp (milliseconds) for TikTok. YouTube uses youtubeThumbnailKey in controls.
- When cross-posting, adjust content length for each platform's limits (X: 280, Bluesky: 300, TikTok: 2200, GBP: 1500).
- If the user doesn't specify a time, suggest tomorrow at 9:00 AM in their timezone.
- Batch up to 15 posts per API call for efficiency.
- Use
firstComment for CTAs and links — keeps the main post clean and gets better engagement.
- X (Twitter) allows only 5 posts per account per day via API — warn the user if they're batching many X posts.
- For draft posts, set
status: "DRAFT" and omit scheduledAt — the user can finalize in the PostFast dashboard.
- GBP always requires
gbpLocationId — fetch locations first with GET /social-media/{id}/gbp-locations.
- GBP supports 3 post types: STANDARD (default), EVENT, and OFFER. EVENT/OFFER need start and end dates.
- GBP only supports 1 image (no video, no carousels) and has a 5-post/day limit.
- Use
GET /social-posts with from/to filters to check what's already scheduled before adding more.
