The Federation Across Networks mini series is complete. Here's everything.
Three posts on how Bluesky, Threads, and Nostr connect to the fediverse, and what each reveals about the limits of cross-protocol federation.
The Federation Across Networks series is complete. Three posts, in the order they should be read:
The Bridge to Bluesky: What Happens When Two Protocols Try to Talk - AT Protocol and ActivityPub aren't the same idea implemented differently. They were built independently to solve different problems. In this post, we take a look at Bridgy Fed - a bridge that attempts to connect ATproto & ActivityPub networks.
Threads Enters the Fediverse (With Caveats) - Meta promised fediverse federation. Then delivered it. But adoption is low - as of early 2025, only 25,900 out of 200 million Threads accounts had opted in. Only ~800 had actually followed a Mastodon account. In this post, we cover Threads entry into the fediverse.
Nostr and the Protocol Bridges - Nostr departs from ActivityPub and AT Protocol at the identity layer: your account is a cryptographic key pair, not a server account. Every action (post, follow, reaction, profile update) is a signed JSON event broadcast over WebSocket to relays. In this post, we cover Nostr's architecture, the relay layer, and the full bridge ecosystem.
The Federation Across Networks series covered the edges of the fediverse where it meets protocols built on different assumptions.
The next series, The Fediverse Beyond Mastodon, stays entirely within ActivityPub and maps what's already there.
Mastodon has roughly a million, monthly active users. Pixelfed, PeerTube, Lemmy, the Misskey family, Pleroma, Ghost, WriteFreely, Bookwyrm, NodeBB — they're all on the same network, federating with each other and with Mastodon, built for different people with different assumptions about what social networking is for.
Four post mini series, The Fediverse Beyond Mastodon, starts next week.
