Threads vs Bluesky vs Mastodon: Which One Is Worth Your Time?

Threads is by far the biggest of the three, Bluesky is the one growing fastest from a smaller base, and Mastodon is the one nobody owns. If you only want reach, Threads wins on size alone. If you want an open API you can build on without a review queue, Bluesky is the easiest of the three by a wide margin.

They all look like the same product. They behave very differently once you post to them regularly.

How big is each one?

Note: Figures here were verified against Meta’s Q2 2026 earnings call (July 2026), Bluesky’s own company blog (July 2026), and each platform’s published API documentation as of September 2026. Platforms change these without notice.

Two honest caveats on that table. Bluesky’s figure is registered accounts, not monthly actives, and those are not the same metric: a registered-account count always flatters a platform. Mastodon does not publish a headline active-user number on its own site, and the figures that circulate come from third-party crawlers of the network, so we are not quoting one here. What is safe to say is that Mastodon’s active population is one to two orders of magnitude below the other two.

What is each one actually good at?

Threads is a distribution channel. It inherits your Instagram graph, which means a new account starts with an audience instead of an empty room. That is its single biggest advantage and it is a large one. The cost is that the feed is heavily algorithmic and links have historically been de-emphasised, so it rewards conversation over traffic.

Bluesky is the developer’s network. It is built on the AT Protocol, which is genuinely open: you can read the firehose, run your own feed algorithm, host your own data server, and write a posting client without asking permission. Custom feeds are the feature that keeps people there, because you can subscribe to a feed somebody else built rather than accepting one ranking.

Mastodon is the one you can’t be evicted from. Servers are run by individuals and organisations. Nobody can change the terms on all of them at once. The trade is that discovery is genuinely hard, your reach depends partly on which server you joined and who it federates with, and the whole thing asks more of a newcomer than either of the others.

Which has the better API?

This is where they separate most sharply.

Bluesky has no app review. You authenticate with an app password or an OAuth session, upload a blob, and create a record. There is no business verification, no screencast, no waiting. For a developer that difference is worth weeks. We wrote up the mechanics in the Bluesky API post tutorial.

Threads uses Meta’s app model. That means a Meta developer app, permission review, and a long-lived access token you have to refresh on a schedule. It works well once it is set up. Getting it set up is the expensive part. Details in the Threads API guide.

Mastodon sits in between. Each server exposes the same REST API, and you register an application against a specific server rather than a central platform. There is no review, but there is also no single endpoint: your integration has to handle per-server base URLs and per-server limits.

Can you just post to all three?

Mostly, yes, and a lot of people do. The three are close enough in shape that one text post usually works everywhere.

The two constraints worth knowing before you automate it. Bluesky’s 300-character limit is the tightest, so it is the one that decides your ceiling if you want identical text everywhere. And Bluesky does not auto-detect links or mentions: they have to be marked up as facets with byte offsets, which is why a naive cross-post to Bluesky often arrives with a dead-looking URL.

If you are already posting to one and want the others, the practical guides are cross-posting Threads to Bluesky and cross-posting from X to Bluesky.

Check your text against the tightest limit first with the Bluesky character counter.

The verdict: who should pick which?

There is no winner here, because the three optimise for different things.

Pick Threads if you want reach and you already have an Instagram audience. It is the only one of the three where a new account can get in front of a lot of people quickly, and for most brands that decides it. Accept that you are a tenant.

Pick Bluesky if you are technical, or if your audience is. Tech, journalism, science and open-source communities moved there in numbers that matter relative to its size, so engagement per follower tends to be better than the raw account count suggests. It is also the only one of the three you can build on in an afternoon.

Pick Mastodon if independence is the point. Not as a growth channel: it is not one. As a place your account cannot be taken away and your posts are not being ranked by an advertising business. That is a real reason, and it is not the same reason as the other two.

Pick more than one if the content is text. Text cross-posts almost losslessly between all three. The cost of adding a second network here is close to zero, which is not true of video platforms.

The short version

Threads has the audience, at 500 million monthly actives. Bluesky has over 43 million registered accounts, a much smaller but unusually engaged and technical base, and the only genuinely open API of the three. Mastodon has no owner and no meaningful discovery, which is simultaneously its point and its problem. Text posts move between all three cheaply, so treat this as “which is primary” rather than “which one”.

Scheduling all three from one place

BulkPublish supports all three alongside 12 other networks, so a post written once can be queued to Threads, Bluesky and Mastodon in the same action, with each platform’s limit checked before it goes out rather than after it fails. Per-platform text overrides exist for the cases where the 300-character ceiling bites. See scheduling for the queue model.

Related

• Threads vs X
• Bluesky vs X
• Cross-post Threads to Bluesky
• Bluesky character limit
• How to schedule Mastodon posts