JavaScript Libraries

JavaScript/TypeScript libraries for implementing ActivityPub.

Fedify

Comprehensive TypeScript framework for ActivityPub servers.

Property	Value
Repository	github.com/dahlia/fedify
Documentation	fedify.dev
License	MIT
Status	Active, Production Ready

Features

• Full TypeScript support with type-safe Activity Vocabulary
• Deno, Node.js, and Bun compatible
• Framework adapters (Express, Fastify, Hono, Koa, SvelteKit)
• HTTP Signatures, LD Signatures, Object Integrity Proofs
• Database integrations (PostgreSQL, SQLite, Redis)
• Built-in WebFinger, NodeInfo

See dedicated Fedify page for full documentation.

activitypub-express

Express.js middleware for ActivityPub.

Property	Value
Repository	github.com/immers-space/activitypub-express
License	MIT
Status	Active

Features

• Express.js integration
• MongoDB storage
• WebFinger support
• Activity delivery

Example

const express = require('express');
const ActivitypubExpress = require('activitypub-express');

const app = express();
const apex = ActivitypubExpress({
  domain: 'example.com',
  actorParam: 'actor',
  objectParam: 'id',
});

app.use(apex);

app.route(apex.routes.actor)
  .get(apex.net.actor.get)
  .post(apex.net.actor.post);

app.route(apex.routes.inbox)
  .get(apex.net.inbox.get)
  .post(apex.net.inbox.post);

microfed

Minimal, modular ActivityPub microservices library.

Property	Value
Repository	github.com/micro-fed/microfed.org
npm	microfed
License	MIT
Status	Active

Features

• Zero dependencies (uses Node.js crypto)
• Modular exports (profile, auth, webfinger, inbox, outbox)
• HTTP Signature signing and verification
• WebFinger resolution
• Activity creation and delivery

Example

import { profile, auth, webfinger, outbox } from 'microfed';

// Generate keypair
const { publicKey, privateKey } = auth.generateKeypair();

// Create actor
const actor = profile.createActor({
  id: 'https://example.com/alice#me',
  username: 'alice',
  name: 'Alice',
  publicKey
});

// Create and sign a post
const note = outbox.createNote({
  actor: actor.id,
  content: '<p>Hello!</p>'
});

// Sign HTTP request
const headers = auth.sign({
  privateKey,
  keyId: 'https://example.com/alice#main-key',
  method: 'POST',
  url: 'https://remote.example/inbox',
  body: JSON.stringify(note)
});

Modular Imports

// Import only what you need
import { sign, verify } from 'microfed/auth';
import { createActor } from 'microfed/profile';
import { resolve } from 'microfed/webfinger';

as2

ActivityStreams 2.0 vocabulary library.

Property	Value
Repository	github.com/jasnell/activitystrea.ms
npm	activitystrea.ms
Status	Maintenance

Example

const as2 = require('activitystrea.ms');

const note = as2.note()
  .name('My Note')
  .content('Hello, World!')
  .get();

console.log(JSON.stringify(note, null, 2));

http-signature

HTTP Signature implementation.

Property	Value
Repository	github.com/joyent/node-http-signature
npm	http-signature
Status	Stable

Signing

const httpSignature = require('http-signature');
const https = require('https');

const options = {
  host: 'remote.example',
  path: '/inbox',
  method: 'POST',
  headers: { 'Content-Type': 'application/activity+json' }
};

const req = https.request(options);

httpSignature.sign(req, {
  key: privateKey,
  keyId: 'https://example.com/users/alice#main-key',
  headers: ['(request-target)', 'host', 'date', 'digest']
});

Verification

httpSignature.parseRequest(req);
httpSignature.verifySignature(parsed, publicKey);

jsonld

JSON-LD processor.

Property	Value
Repository	github.com/digitalbazaar/jsonld.js
npm	jsonld
Status	Active

Example

const jsonld = require('jsonld');

// Expand a document
const expanded = await jsonld.expand(activity);

// Compact with context
const compacted = await jsonld.compact(expanded, {
  "@context": "https://www.w3.org/ns/activitystreams"
});

Comparison

Library	Use Case	Complexity	Features
Fedify	Full server	High	Complete framework
activitypub-express	Express apps	Medium	Middleware
microfed	Minimal server	Low	Modular primitives
as2	Types only	Low	Vocabulary
http-signature	Signing	Low	HTTP Signatures

Quick Start Recommendation

For new projects: Use Fedify for comprehensive TypeScript support.

For existing Express apps: Use activitypub-express.

For minimal/single-user: Use microfed with Fedbox.

For manual implementation: Combine http-signature + jsonld + custom code.

See Also

• Libraries Overview
• Building an Actor