Platforms
Platform keys, character limits, and supported content types across all 15 platforms.
Every entry in a post's post_contents names its platform with one of these
keys. Character limits and media capabilities differ per platform. The table
below is the quick view; the machine-readable truth is
GET /platforms, which
returns capabilities (character limits, content types, image counts, media
content-type and size limits) so clients don't hardcode them.
| Platform | Key | Char limit | Text | Images | Video | Notes |
|---|---|---|---|---|---|---|
| X (Twitter) | twitter | 280 | ✅ | up to 4 | ✅ | Threads, communities via community_id |
linkedin | 3,000 | ✅ | up to 20 | ✅ | Polls, PDF document posts, org pages | |
instagram | 2,200 | ❌ | 1–10 carousel | ✅ | Reels, Stories, first comment; caption only | |
| Threads | threads | 500 | ✅ | up to 10 | ❌ | Reply chains, quote posts via quote_post_id |
| YouTube | youtube | 5,000 | ❌ | ❌ | ✅ | Video only |
pinterest | 800 | ❌ | 1 | ✅ | Board via board_id; video pins need a cover image | |
| TikTok | tiktok | 2,200 | ❌ | up to 35 | ✅ | |
| Bluesky | bluesky | 300 | ✅ | up to 4 | ❌ | Reply threads |
| Mastodon | mastodon | 500 | ✅ | up to 4 | ❌ | |
facebook | 63,206 | ✅ | multi-image | ❌ | Pages | |
| Google Business | google_business | 1,500 | ✅ | ❌ | ❌ | Business profile updates |
| Discord | discord | 2,000 | ✅ | up to 10 | ❌ | Posts via channel webhook |
| Telegram | telegram | 4,096 | ✅ | up to 10 | ❌ | |
| Tumblr | tumblr | 4,096 | ✅ | up to 10 | ✅ | |
| Slack | slack | 4,000 | ✅ | up to 10 | ❌ |
A content_type on each post_contents entry declares what the entry is:
text, single_image, multi_image, video, or document. Platforms
reject content types they don't support at validation time; a dry run
surfaces this before anything goes live (see
Scheduling).
One post, many platforms
A single post carries one post_contents entry per platform, each with
its own body and metadata, plus social_account_ids for the accounts to
publish through. That is how the same post fits X's 280 characters and
LinkedIn's 3,000 in one API call.
Platform-specific options
Attachment references and per-platform options ride in each entry's
metadata object: media_id (X), asset_urn / document_urn (LinkedIn),
r2_key (storage uploads), board_id (Pinterest), community_id (X),
quote_post_id (Threads). X additionally accepts reply_settings
(following, mentionedUsers, subscribers, or verified; omit the field
for everyone) and the boolean disclosure labels made_with_ai and
paid_partnership, sent only when true. See
Media for how uploads produce these references.