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FOSSE is a WordPress plugin that simplifies Social Web publishing. It gives site owners one place to configure how WordPress posts are represented across federated networks, then routes publishing through the right backend for each protocol.

It bundles wordpress-activitypub and wordpress-atmosphere so a site can publish to ActivityPub networks such as Mastodon and AT Protocol networks such as Bluesky from one WordPress plugin, without managing separate plugin surfaces for each network.

Repository: https://github.com/Automattic/fosse

Requirements

• PHP 8.2+
• WordPress 6.9+
• Composer
• Node.js 20+ with Corepack / pnpm

Use

Install and activate FOSSE like a normal WordPress plugin. For a distributable build, run:

composer run-script build-zip

That creates build/fosse.zip, which can be uploaded or unpacked into wp-content/plugins/.

After activation, go to FOSSE in wp-admin:

• Settings configures ActivityPub actor mode, federated post types, and Bluesky connection.
• Status shows the available providers and connection health.
• The first-run wizard walks through the basic ActivityPub and Bluesky setup.

See the FOSSE Publishing FAQ for how fediverse publishing works, how it differs from Bluesky, and how to edit the site fediverse profile.

Local Setup

corepack enable
composer install
composer install --working-dir=tools
pnpm install

For the first end-to-end test run, install Chromium:

pnpm exec playwright install --with-deps chromium

Test

composer run-script test-php     # PHPUnit via WorDBless
pnpm test                        # Jest
pnpm run test:e2e                # Playwright + WordPress Playground

Before pushing, run the lint checks:

composer run-script lint-php
pnpm run format:check
pnpm run lint

Notes

• src/ contains FOSSE's glue code and admin UI.
• bundled/ contains vendored upstream plugin builds; do not edit it directly.
• See CONTRIBUTING.md and AGENTS.md for workflow, coding standards, CI details, and upstream contribution policy.