| TikTok | ||
|---|---|---|
| Characters | 2,000 | 2,200 |
| Media | optional | a video (required) |
| Hashtags | 1-3 hashtags | max 5 hashtags, inside the caption (comments are invisible to the algorithm) |
| Links in body | fine | fine |
| Needs platform approval | yes | yes |
Facebook posts are frequently text-only. TikTok requires a video on every post, so there is no direct equivalent — you have to attach media before this cross-post is even possible.
Facebook: 1-3 hashtags. TikTok: max 5 hashtags, inside the caption (comments are invisible to the algorithm). Carrying the tag block across is the single most obvious sign of an automated cross-post.
TikTok requires a separate title (max 150 characters). Facebook has no such field, so there is nothing to copy across — it has to be written.
Facebook is warm and community-toned; 40-80 characters peaks engagement. TikTok is hook-first, not SEO-first: the first 80-100 characters decide everything. 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.
curl -X POST https://postwire.io/api/post \
-H "Authorization: Bearer $POSTWIRE_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"platforms": ["facebook", "tiktok"],
"text": "Your post",
"per_platform": {
"facebook": { "text": "The Facebook version" },
"tiktok": { "text": "The TikTok 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.
PostWire takes one idea and publishes a version written for each network — the right length, hashtags and format per platform. It also refuses posts that would fail, like a video network with no video, before they are queued.
Free for one brand — 30 posts a month, no card. Starter is $9/month for three brands and 300 posts. There is a REST API and an MCP server if you would rather automate it.
Start free — no card →Other pairs: TikTok to Facebook · all combinations · which APIs need approval
Most tools that do this bill per connected profile. What that actually costs once you add a second brand is worth reading first.