How to cross-post between Bluesky and Mastodon

Three ways to be on both without writing everything twice — bridging, scheduling to both, or posting natively. What each costs you.

Bluesky and Mastodon are built on different protocols that cannot talk to each other directly. Bluesky uses the AT Protocol; Mastodon uses ActivityPub. If you want an audience on both, something has to bridge the gap — and your three options have genuinely different trade-offs.

Option 1: bridge the accounts

Bridgy Fed sits between the two protocols and translates. It is opt-in on both sides, free, and once enabled your posts appear on the other network without you doing anything. People over there can follow, reply and boost, and you see it back.

It is the least effort by a distance. It also has edges worth knowing before you rely on it:

• Edits do not propagate. Mastodon supports editing a post; Bluesky does not. Fix a typo on Mastodon and the bridged copy keeps the typo.
• Direct messages do not cross. The two protocols handle private messaging differently enough that bridging them is not supported.
• Quote posts from Mastodon do not bridge, because the two sides implement quoting differently.
• Everything goes. A bridge is all-or-nothing. You cannot send some posts and hold others back.

That last one is the real decision. If your Bluesky voice and your Mastodon voice are the same, a bridge is excellent. If they are not — and for a lot of people they genuinely are not — it is the wrong tool.

Option 2: schedule to both

Write once in a tool that publishes to both networks natively. Each post is a real native post on each side: no bridge, no proxy account, no translation layer, and full control over which post goes where.

The thing to check is whether the tool respects each network properly, because they are not the same and pretending they are produces bad posts:

• Different limits. 300 on Bluesky, 500 on Mastodon by default. A tool that counts to one number is wrong on the other.
• Different counting rules. Bluesky counts grapheme clusters; Mastodon counts links as 23 and ignores mention domains.
• Content warnings are Mastodon-only. There is no Bluesky equivalent, and a tool that drops the CW silently is worse than one that refuses.
• Per-network text. The ability to send a shorter version to Bluesky and a longer one to Mastodon, from one composer, is the thing that makes this approach better than posting twice.

This is what PostDaily does, so treat that as disclosure rather than a recommendation — but the checklist above is worth applying to whatever you pick.

Option 3: post to each natively

Open both apps and write twice. Genuinely the best output, genuinely the most work, and it does not scale past a few posts a week.

Worth saying plainly because the other two options are often sold as strictly better and they are not. Writing for a specific audience beats syndicating to a general one, every time. The question is whether you can sustain it.

Which to choose

• Same voice on both, low effort wanted — bridge them.
• Different emphasis per network, or you want to plan ahead — schedule to both.
• Small volume, high care — post natively and do not automate it.

One thing everyone gets wrong

Cross-posting is not a distribution strategy on its own. The networks have different cultures — they differ more than they look — and a stream of posts that obviously came from somewhere else reads exactly like that. The people who do this well cross-post the durable things and write natively for the conversational ones.

"Automate the posts that would be the same anywhere. Write the rest where they belong."

The mechanical differences that trip people up

Whichever route you take, four things do not translate cleanly between the two networks, and knowing them in advance saves a lot of confusion:

• Content warnings have no Bluesky equivalent. A CW either gets dropped or folded into the post text. Neither is what you meant.
• Editing only exists on Mastodon. Anything bridged or duplicated to Bluesky is frozen once posted.
• Mentions do not resolve across networks. Mentioning a Mastodon user in a post that lands on Bluesky produces text, not a link to anyone.
• Alt text should travel, and sometimes does not. Check it once with a real image rather than assuming.

Replies are the part people forget

Getting posts onto both networks is the easy half. The half that determines whether being on both is worth it is whether you see and answer the replies.

A bridge does carry replies back, which is its real advantage over scheduling to both — with a scheduler you have two sets of conversations in two apps, and one of them will get neglected. Be honest about whether you will actually check both before adding a second network.