Fedipub is an open-source Ruby library that implements ActivityPub as a pluggable engine for Ruby on Rails. Developers can add federation to an existing Rails app — or start a new one — using Rails idioms instead of a one-off protocol stack.

The library already runs in production applications to some extent. Scope: documentation and onboarding, the rest of the core ActivityPub standard, and common Fediverse enhancements. Source: gitlab.com/fedipub/fedipub. Run by Manyfold; project site floppy.org.uk.

Most new social apps still ship as silos because implementing ActivityPub from scratch is expensive. Fedipub lowers that cost for the Rails ecosystem, so federation is a library choice rather than a rewrite. That undercuts lock-in: users on a Fedipub-backed app can reach the rest of the Fediverse instead of starting a private graph that only one operator controls.