Libraries & SDKs Overview

ActivityPub libraries by language, with their maintenance status.

:::info How status is measured Versions and status were taken from package registries (npm, PyPI, crates.io, RubyGems, Packagist, the Go module proxy) and GitHub/Codeberg/GitLab on 2026-10-15.

• Active — a release or commit in the last 12 months
• Dormant — last activity 12–36 months ago
• Unmaintained / Archived — no activity for over 3 years, or the repository is archived

Libraries change fast; check the repository before you depend on one. :::

By Language

JavaScript / TypeScript

Library	What it is	Latest	Status
Fedify	Full ActivityPub framework	2.4.4 (2026-10)	Active
BotKit	Bot framework on Fedify	0.5.7 (2026-10)	Active
activitystrea.ms	AS2 builder/parser	4.0.2 (2026-10)	Active
microfed	Minimal primitives (by the SocialDocs maintainer)	0.0.14 (2025-12)	Experimental
activitypub-express	Express middleware	4.4.2 (2024-02)	Dormant

More JavaScript libraries →

Python

Library	What it is	Latest	Status
federation	Multi-protocol (ActivityPub, Diaspora)	0.27.0 (2026-03)	Active
http-message-signatures	RFC 9421 signatures	2.0.1 (2026-01)	Active
bovine	Async ActivityPub toolkit	0.5.19 (2025-09)	Dormant
apkit	ActivityPub toolkit	0.3.8 (2026-02)	Archived
little-boxes	ActivityPub toolkit	0.1.0 (2018)	Archived

More Python libraries →

Go

Library	What it is	Latest	Status
go-ap	Modular packages + FedBOX server	commits 2026-10	Active
GoToSocial's activity fork	Maintained fork of go-fed/activity	v1.19.0 (2026-01)	Active
GoToSocial's httpsig fork	Maintained fork of go-fed/httpsig	v1.5.0 (2025-10)	Active
go-fed/activity	Original vocabulary + middleware	v1.0.0 (2020)	Unmaintained

More Go libraries →

Rust

Library	What it is	Latest	Status
activitypub_federation	Lemmy's federation framework	0.6.6 (2026-10)	Active
http-signature-normalization	draft-cavage signatures	0.7.1 (2026-06)	Active
activitystreams	AS2 types	0.6.2 (2020); 0.7 alpha (2023)	Unmaintained

More Rust libraries →

Ruby

Library	What it is	Latest	Status
Fedipub (formerly Federails)	Rails engine	0.10.0 (2026-09)	Active
linzer	RFC 9421 signatures	0.8.1 (2026-08)	Active
Mastodon	Reference server (not a library)	—	Active

More Ruby libraries →

PHP

Library	What it is	Latest	Status
ActivityPub for WordPress	WordPress plugin	9.3.1 (2026-09)	Active
ActivityPhp	Types + server toolkit	0.8.1 (2025-10)	Active
Pixelfed	Reference server (Laravel)	—	Active

More PHP libraries →

Elixir, C# and others

Library	What it is	Status
activity_pub (Bonfire)	Elixir library	Active (work in progress)
Letterbook	C# server (reference)	Active

More languages →

Choosing a Library

For Production

• TypeScript: Fedify
• Rust: activitypub_federation
• Go: go-ap, or GoToSocial's forks of the go-fed libraries
• Ruby on Rails: Fedipub
• WordPress: the ActivityPub plugin

For Prototypes and Bots

• Bots: BotKit
• Python: federation, or bovine if you accept its slower pace

For Learning

Read a maintained server:

• GoToSocial (Go)
• Mastodon (Ruby) — the de facto interop target
• Lemmy (Rust)
• Hollo (TypeScript, built on Fedify)

What Libraries Provide

Core Features

• ActivityStreams type definitions
• JSON(-LD) serialization and parsing
• WebFinger client/server

Federation Features

• HTTP signing and verification (draft-cavage; increasingly also RFC 9421)
• Inbox handling and delivery queues with retries
• Fetching and caching remote objects

The security-critical parts are request verification and origin checks. A good library does these for you; if you build them yourself, read issue #37 first.

Building Without a Library

If no library fits your needs, you can implement from scratch:

1. Start simple: WebFinger + Actor endpoint
2. Add inbox: Receive and verify activities
3. Add signing: HTTP Signatures
4. Add delivery: Queue and retry sends to other servers

See the implementation guides and Other Libraries.

See Also

• JavaScript Libraries
• Python Libraries
• Go Libraries
• Choosing Your Stack