The decentralized social network known as the Fediverse is a collection of “instances”, or servers, independently operated but all speaking a common protocol to allow users to follow and share across different instances.

As well as social microblogging and photo/video sharingsites, the Fediverse includes other types of instances; all sorts of social sites like event planning can have a Fediverse presence, and other sites like this blog can be Federated to share new content automatically.


The main protocol is called ActivityPub. This is the magic that lets users find & follow one another across instances.

The WebFinger protocol is used to find user profiles and some API end points, including the user’s in- and outbox, and their “external interaction” url, which allows users to follow accounts from other instances.

Instance information is provided in a few places; first is the Nodeinfo protocol, which gives a rundown of the instance’s capabilities, services, and protocols; there are also instance-info endpoints in some platform APIs, like Mastodon’s `/api/v1/instance` endpoint, which give more platform-specific properties for the instance.

There is a lot of overlap; for instance, Pleroma can support the full Mastodon API, for clients and S2S, as well as its own client and S2S protocol.


Fediverse instances provide a number of well-known api endpoints to begin discovery: nodeinfo for service discovery, and WebFinger for user data.


  • Fedi Follow & Share – a standalone widget to make it easier for users to follow & share Federated sites, like this blog
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