What is the Atmosphere?

The open network Sifa runs on. One account works across Sifa, Bluesky, and dozens of others. Move providers, keep your handle, keep your followers, keep your work.

Sifa is one app inside the Atmosphere: an open network of apps and services that all share the same account system. Bluesky, Tangled, Leaflet, Eurosky, Smoke Signal, Sifa, and however many more launch this year. They speak the same protocol (the AT Protocol, if you want the technical name) and read from the same pool of data.

If you have a Bluesky account, you have a Sifa account. Sign in once, you're home everywhere. Sifa doesn't run its own login.

Walled garden vs shared foundation

A regular social platform is a walled garden: your account, your posts, your followers all live inside one company's database. Move to a competitor and you start over.

The Atmosphere swaps that for a shared foundation. Your account, your posts, your followers, your professional history all live in a place you control. Apps read from it and write to it on your behalf. Sifa is one of those apps. So is Bluesky. So is the next app launching tomorrow.

Your followers are yours, not rented from a platform

When you build an audience on LinkedIn, that audience is LinkedIn's. Stop paying LinkedIn, lose access to its app, get suspended by LinkedIn moderation, and you can't take your network with you.

On the Atmosphere, your followers are stored on your account. They follow your DID (a permanent identifier), not your handle, not the app you're using. Move from Sifa to a different professional-network app tomorrow and the same followers are there, ready to see your work. You can't lose them unless you delete them yourself.

Post once, show everywhere

When you publish on the Atmosphere, the record goes to your account. Any app that reads that record type can render it however it wants.

Concretely on Sifa:

A blog post you publish on Leaflet or WhiteWind appears in your Sifa activity feed without you cross-posting.
A project you list in your Sifa profile is readable by any app that wants to build a CV generator, a portfolio page, a job board.
An endorsement you give on Sifa is its own record on your account. A third-party reader could surface it, embed it, or fact-check it.

You write once, every Atmosphere app gets the same source of truth.

Choose your provider, switch any time

Your account data lives with a provider (sometimes called a PDS, Personal Data Server). The provider runs the server that stores your records and keeps them available to every app.

You pick the provider:

Bluesky (US-hosted, the default for most people today).
Eurosky (EU-hosted, GDPR-aware).
Tangled (EU-hosted, developer-focused).
Blacksky (community-run).
...or self-host on your own server.

The provider isn't tied to the app. You can have a Bluesky account hosted on Eurosky's provider. Or a Sifa profile hosted on your own server. And you can move between providers at any time without losing followers, posts, or any other data. The protocol is built for migration; we have a walkthrough when you're ready.

Three concepts to learn

Open networks have a bit more surface area than walled gardens. Three terms come up often. The next page explains each in plain language:

A handle (alice.bsky.social, or alice.com if you own a domain).
A provider (where your data lives, see above).
A DID (the permanent ID under your handle, never changes).

Apps like Sifa hide them most of the time, but knowing what each is unlocks the rest of the network.

Locked open by design

The Atmosphere isn't owned by any single company. Account ownership, app choice, moderation choice, provider choice: all of them are in your hands by design, not as a favour from a platform that could revoke it tomorrow.

That's the bet Sifa is built on. Your professional identity should outlast the apps you use to show it.

Where to next

DIDs, handles, and providers: the three parts of an Atmosphere identity.
Apps, AppViews, and the firehose: how multiple apps render the same data differently.
Your data on a provider: what records look like and how to inspect them.
Lexicons and integrations: the open schemas that hold it together.

Outside this site:

atmosphereaccount.com: general-audience intro to the network, written from the account-portability angle.
Kuba Suder's Introduction to AT Protocol: the canonical long read for developers wanting depth on every layer (records, relays, AppViews, labellers, feed generators, lexicons, DIDs, PLC).
atproto.com: official protocol documentation. Reference-heavy.

Sifa-specific guidance lives here.