What is the Atmosphere?
Updated
In short: the AT Protocol (atproto) is the open technology Bluesky is built on, and the Atmosphere is the name for everything built on it: Bluesky, other social apps, blogs, code, events and music apps, and the servers that host accounts. One account works across all of them, and you can move it without losing your followers.
Bluesky is one app, the AT Protocol is the network
When you sign up for Bluesky, you get an account on the AT Protocol (the "AT" stands for Authenticated Transfer). Bluesky is the best-known app that reads and writes to it, but it's not the only one:
- Other places to host your account, such as Eurosky, W or Blacksky, besides Bluesky's own servers.
- Other apps using the same account: blogs like WhiteWind and Leaflet, Tangled for code, Smoke Signal for events, teal.fm for music, and more.
- Bridges such as Bridgy Fed, which connect the Atmosphere with other networks like Mastodon.
Together, that's the Atmosphere: many apps and hosts, one shared network.
Which Atmosphere apps has an account used?
The bskycheck profile tool shows an account's "Atmosphere footprint": the AT Protocol apps it has used and when, plus where it is hosted and its identity history. Free, no login.
Why it matters for you
- One account everywhere: sign in to other Atmosphere apps with your Bluesky handle, no new account needed.
- Your followers come with you: your identity is a permanent ID, not a server address, so you can change your handle or move to another host and keep your followers and posts.
- Your own domain as your name: any domain you own can be your handle, like yourname.com.
- You choose your experience: custom feeds, community moderation services and other apps are open to anyone to build, so you are not stuck with one company's choices.
How it fits together
- Your identity: a permanent ID (a DID) with a readable handle pointing to it.
- Your data: stored in your account's repository on a server called a PDS. Posts, likes and follows from every Atmosphere app live there, side by side.
- The network: services gather updates from every server and build what apps show: timelines, threads, counts.
- The apps: each app reads what it needs from the network and writes to your repository.
Most of this data is public, which is how bskycheck can show stats about the whole network, like the new accounts across the Atmosphere, live.
Questions
What is the Atmosphere on Bluesky?
The community's name for the network of apps and services built on the AT Protocol: Bluesky, other apps that use the same accounts, and the servers that host them.
What is the AT Protocol?
The open protocol Bluesky is built on ("AT" stands for Authenticated Transfer). It separates your identity, your data and the apps, so accounts can move between servers and many apps can share one network.
Is the AT Protocol the same as Bluesky?
No. Bluesky is an app, and the company that created the protocol. The AT Protocol is open: other companies, communities and individuals build apps and run servers on it.
Can I use my Bluesky account in other apps?
Yes. Apps built on the AT Protocol, such as WhiteWind, Leaflet, Tangled, Smoke Signal or teal.fm, let you sign in with your Bluesky handle.
Is Bluesky like Mastodon?
Both are decentralized, but they use different protocols: Bluesky uses the AT Protocol, Mastodon uses ActivityPub. Bridges such as Bridgy Fed let people on both networks follow each other.
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bskycheck is an independent project, not affiliated with Bluesky. Spotted something out of date? Tell @bskycheck.com.