This is a translation of the article I originally wrote in Russian a year ago.
Lately, after Elon Musk bought Twitter, people have started looking for its alternatives – and many found one in Mastodon.
Mastodon is a decentralized social media platform that works on the federation model, like email. The federation protocol is called ActivityPub and is a W3C standard, and Mastodon is far from being its only implementation, albeit it is the most popular one.

Explore the open social web through the lens of ActivityPub and the fediverse.

Brings together ActivityPub and Solid Pods and empowers developers to create truly decentralized applications.

This article is part of the series Understanding ActivityPub, which takes a look at the ActivityPub protocol through the lens of real-world examples. The protocol exchanges are taken from ActivityPub.Academy, a modified Mastodon instance that shows ActivityPub messages in real time (see the announcement post).

This article is part of the series Understanding ActivityPub, which takes a look at the ActivityPub protocol through the lens of real-world examples. The protocol exchanges are taken from ActivityPub.Academy, a modified Mastodon instance that shows ActivityPub messages in real time (see the announcement post).

Building on the Fediverse is hard. Here is a list of ActivityPub and other developer resources that have been helpful in developing Emissary.
This is not a canonical or official list by any means, but hopefully this list of bookmarks is valuable to others who are building their own Fediverse apps.

ActivityPub in PixelFed.

Fediverse Enhancement Proposals

An ActivityPub debugging instance? Gotta take a look, probably.

Another unfortunate Fediverse developer shares their woes.

This is the codebase for castling.club, an ActivityPub server with a single
hardcoded 'King' service actor that acts as a chess arbiter.

This is a primer for implementation of ActivityPub.

Гришка учит Активитипабу. Вовремя!

Fediverse Developer Network

Kinda incomplete

Tedu's implementation of HTTP signatures which is used in, for example, Honk. Since it's written in Go, is actually used, and licensed under a free license, I'll probably use it for Betula.

Info on HTTP signatures.

Lessons learned from making apps that play nice with the fediverse.

Quickly design and test ActivityPub objects with mock servers of popular projects like Mastodon and Pixelfed.

Thanks, just in time.

List of links about ActivityPub development. I'll need that.

Also this:

• https://flak.tedunangst.com/post/activity-notes
• https://flak.tedunangst.com/post/AP-networking