This post isn’t about the ActivityPub plugin. ATmosphere is a separate plugin from the same small team, for the other half of the open social web: the AT Protocol, the open network behind Bluesky. We’re posting about it here because the audience overlaps and the mission is the same. If there’s enough interest, we’ll spin up a dedicated blog for it. Until then, this is the closest venue.
Today is the public 1.0.0 release on WordPress.org. After months of design notes, internal experiments, and a stretch of focused work alongside the ActivityPub plugin, ATmosphere has cleared the troposphere.
What ATmosphere is
When you publish a post, ATmosphere shares it on Bluesky and stores the full article on your AT Protocol account as a structured record. Bluesky replies, likes, and reposts come back as comments on your WordPress post. Approved comments from logged-in readers go the other way and appear as replies under your original Bluesky post. The same conversation lives in both places without you having to copy anything by hand.
The bet underneath is bigger than cross-posting. ATmosphere publishes site.standard.* lexicon records, so your blog itself becomes AT Protocol data, not just a link shared on Bluesky. Any compatible app can read the full article from your AT Protocol account, the same way it reads a Bluesky post. WordPress becomes a first-class participant in the network, not a visitor.
How this differs from a cross-poster
The first question you may have is: how is this different from Jetpack Social’s Bluesky integration, or from any of the other plugins that share to Bluesky?
The answer is that they’re solving a different problem. A cross-poster gets your content in front of Bluesky users, which is a real and useful thing. But it’s still a broadcast model. Your WordPress site talks at Bluesky, it doesn’t participate in the protocol.
In practice that shakes out two ways. First, a cross-posted update creates a copy, not a connection. The post on Bluesky and the post on WordPress are separate records, and nothing in the protocol ties them together. Second, your blog itself has no identity in the network. The cross-poster authenticates as you, the person, and posts on your behalf. Your blog as an entity, with its archive and structure, is invisible to the protocol.
ATmosphere is built around making your blog itself a participant. Every publish writes two records: an app.bsky.feed.post so the update shows up in Bluesky timelines, and a site.standard.document from the standard.site lexicons that stores the full canonical article on your AT Protocol account. A bskyPostRef link ties the two together. Your blog appears in the network as a publication that other apps and aggregators can discover and read in full, not as a stream of truncated link cards.
If you want a poster, Jetpack Social is the right tool. If you want your WordPress site to be a place on the AT Protocol, that’s what ATmosphere is for.
Why a third-party PDS, for now
There’s a natural follow-up once the model clicks: if my WordPress site is acting as a Bluesky identity, why does Bluesky (or another provider) still need to be in the picture at all? Why not host the data on the site itself?
We tried that route first. About 90% of a Personal Data Server (the AT Protocol service that holds your signed records and streams them to the network) maps cleanly to PHP and a WordPress database. The remaining 10% is the firehose: a WebSocket stream that pushes every change to the network’s relays in real time. PHP’s request-response model is fundamentally incompatible with persistent connections like that, and typical WordPress hosting environments aren’t designed for always-on background processes either.
The cleaner mental model turned out to be email. Even when you self-host your mail, you don’t build the mail server as a WordPress plugin. The mail server is its own piece of infrastructure that runs alongside your site. AT Protocol is the same shape. The PDS is infrastructure, not application logic. ActivityPub was designed to be implementable by any HTTP server, which is why it works as a plain WordPress plugin. AT Protocol was designed around always-on data servers, so the natural fit is a hosted PDS running next to WordPress, not inside it.
For 1.0.0, that means using whichever PDS the user already has. Most people connecting ATmosphere come in with a Bluesky account, so they already have a PDS and a DID, and borrowing that lets us focus on the parts that live on the WordPress side: the publishing pipeline, the long-form rendering, the comment round trip, the domain-as-handle handshake.
We are still pulling on a thread, though. There’s a version of this where a PDS sits comfortably alongside WordPress, ready to host your records for you, so the AT Protocol side feels just as native to WordPress as the ActivityPub side already does. Nothing to announce yet. We’ll let you know when there’s something to show 😉
Your domain, your handle
One of the headline features: your WordPress domain becomes your Bluesky handle. Instead of @you.bsky.social, your handle reads @yourblog.com.
ATmosphere handles the verification side. It serves the right file at /.well-known/atproto-did so Bluesky can confirm the domain really belongs to you. From the settings page, it’s one click. You then open Bluesky, pick Change Handle, choose I have my own domain, enter your site, and you’re done. Same identity model Bluesky uses for its own custom domains, but the technical bit takes care of itself.
Long posts, done right
The hardest problem in WordPress-to-Bluesky publishing is what to do with a long article on a 300-character network. ATmosphere gives you three options from the settings page:
- A link card, the default. A clean preview pointing back to your full post.
- A single post combining the body text and the permalink, for when the post fits.
- A two-post teaser thread: a hook, a body chunk, and a “continue reading” reply with the link card. The teaser surfaces reliably on bsky.app profiles, and the terminal post always offers a clear path back to the full article on your site.
When you edit a threaded post, ATmosphere updates the existing Bluesky posts in place when it can, so links and replies stay connected. If you change the publishing format, ATmosphere replaces the old posts with new ones. And the full article, every paragraph of it, lives on your AT Protocol account regardless of which format you pick, so other AT Protocol-aware apps and readers can render the long version too.
Two-way conversations
When someone replies, likes, or reposts your post on Bluesky, ATmosphere checks periodically and turns those reactions into WordPress comments on the matching post. Likes and reposts get their own comment types, so they show up as engagement counts rather than duplicating as text comments.
Going the other way: when a logged-in reader leaves an approved comment on a cross-posted article, it’s published to Bluesky as a reply under your original post. Edits sync. Unapprove or delete, and the corresponding Bluesky reply comes down too. Anonymous comments, trackbacks, and pingbacks are skipped. Only logged-in readers participate in the round trip.
A few more things worth knowing
- Backfill. A built-in tool publishes older posts to AT Protocol on demand, batched to ten at a time so it doesn’t overwhelm your server.
- Post types. Choose which post types publish to AT Protocol from the settings page. Plugins and themes can opt their own custom post types in with
add_post_type_support( 'your_type', 'atmosphere' ). - Extensible. New
atmosphere_publish_post_resultandatmosphere_publish_comment_resultactions let other code react to publish success or failure. Anatmosphere_should_sync_replyfilter lets you suppress specific incoming replies before they become comments.
Get It
Download from WordPress.org or grab the source on GitHub.
A dedicated blog?
This blog has always been about the ActivityPub plugin, and ATmosphere is a different plugin for a different protocol, so this post is something of a guest appearance. If readers tell us they want ongoing release posts, deep dives, and roadmap notes about ATmosphere too, we’ll spin up a dedicated home for it. For now, follow along here and let us know.
A huge thank-you to everyone who shaped 1.0.0, especially Brandon Kraft (@kraft) and Ryan Cowles, who carried huge pieces of the onboarding, settings, and publishing work over the last few months. Thanks also to the AT Protocol and Bluesky folks who’ve been generous with their time on the lexicon questions.
Try it out, point your domain at Bluesky, publish a post, and tell us what you think. What should ATmosphere do next?
ActivityPub for WordPress 
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