Works, with rewrites

Cross-posting TikTok to Facebook: what actually breaks

You can, but not by copying the text across: 2 things change between TikTok and Facebook, starting with you lose 200 characters. Below is exactly what breaks and what to do instead.

Side by side

TikTokFacebook
Characters2,2002,000
Mediaa video (required)optional
Hashtagsmax 5 hashtags, inside the caption (comments are invisible to the algorithm)1-3 hashtags
Links in bodyfinefine
Needs platform approvalyesyes

What changes, one by one

You lose 200 characters

TikTok allows 2,200 characters; Facebook caps at 2,000. A post written to TikTok's length gets truncated — usually mid-sentence — unless it is rewritten, not trimmed.

The hashtag rules are not the same

TikTok: max 5 hashtags, inside the caption (comments are invisible to the algorithm). Facebook: 1-3 hashtags. Carrying the tag block across is the single most obvious sign of an automated cross-post.

Why copy-paste cross-posting underperforms

TikTok is hook-first, not SEO-first: the first 80-100 characters decide everything. Facebook is warm and community-toned; 40-80 characters peaks engagement. Those are different jobs, so the same words cannot do both well — and every algorithm here demotes text that obviously was not written for it. The fix is not to skip cross-posting; it is to send a native version to each network.

Publish to both in one call

curl -X POST https://postwire.io/api/post \
  -H "Authorization: Bearer $POSTWIRE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "platforms": ["tiktok", "facebook"],
    "text": "Your post",
    "per_platform": {
      "tiktok": { "text": "The TikTok version" },
      "facebook": { "text": "The Facebook version" }
    }
  }'

PostWire's /api/generate writes those per-platform versions for you from a single prompt, respecting every limit in the table above. From an AI agent it is one MCP tool call.

Get an API key free →

Questions people actually ask

Can I cross-post from TikTok to Facebook?
You can, but not by copying the text across: 2 things change between TikTok and Facebook, starting with you lose 200 characters. Below is exactly what breaks and what to do instead.
What is the character limit difference between TikTok and Facebook?
TikTok allows 2,200 characters and Facebook allows 2,000.
How do I post to TikTok and Facebook at the same time?
With PostWire, one API call publishes to both: POST /api/post with platforms set to ["tiktok","facebook"]. Or one MCP tool call from an AI agent.

Other pairs: Facebook to TikTok · all combinations · which APIs need approval