What is the character limit difference between Bluesky and X?

Bluesky allows 300 characters and X allows 280.

How do I post to Bluesky and X at the same time?

With PostWire, one API call publishes to both: POST /api/post with platforms set to ["bluesky","x"]. Or one MCP tool call from an AI agent.

Works, with rewrites

How to post from Bluesky to X

You can, but not by copying the text across: 4 things change between Bluesky and X, starting with you lose 20 characters. Below is exactly what breaks and what to do instead.

Side by side

	Bluesky	X
Characters	300	280
Media	optional	optional
Hashtags	1-2 specific hashtags	1-2 hashtags, zero is fine
Links in body	fine	suppress reach
Needs platform approval	no	yes

What changes, one by one

You lose 20 characters

Bluesky allows 300 characters; X caps at 280. A post written to Bluesky's length gets truncated — usually mid-sentence — unless it is rewritten, not trimmed.

The hashtag rules are not the same

Bluesky: 1-2 specific hashtags. X: 1-2 hashtags, zero is fine. Carrying the tag block across is the single most obvious sign of an automated cross-post.

A link in the body suppresses reach on X

Links are fine on Bluesky. On X they cut distribution — the link belongs in a reply, not in the post.

X needs approval, Bluesky does not

You can post to Bluesky today with a credential you generate yourself. X gates posting behind a platform review — see our API approval notes for what that actually takes.

Why copy-paste cross-posting underperforms

Bluesky is indie and anti-corporate — polished brand voice reads badly. X is one hook and nothing else — opinionated, conversational, over in a breath. 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": ["bluesky", "x"],
    "text": "Your post",
    "per_platform": {
      "bluesky": { "text": "The Bluesky version" },
      "x": { "text": "The X 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.

Do this without writing the post twice

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 →

Questions people actually ask

Can I cross-post from Bluesky to X?: You can, but not by copying the text across: 4 things change between Bluesky and X, starting with you lose 20 characters. Below is exactly what breaks and what to do instead.
What is the character limit difference between Bluesky and X?: Bluesky allows 300 characters and X allows 280.
How do I post to Bluesky and X at the same time?: With PostWire, one API call publishes to both: POST /api/post with platforms set to ["bluesky","x"]. Or one MCP tool call from an AI agent.

Other pairs: X to Bluesky · all combinations · which APIs need approval

Picking a tool for this? We compared the ones with a public API side by side in the alternatives guide, prices included.