Software

Advanced forum / community solution based on Ruby and JS. ([Demo](https://try.discourse.org/), [Source Code](https://github.com/discourse/discourse))

Powerful open source social networking engine. ([Source Code](https://github.com/Elgg/Elgg))

Enigma 1/2 is a modern, multi-platform BBS engine with unlimited "callers" and legacy DOS door game support. ([Source Code](https://github.com/NuSkooler/enigma-bbs))

Delightfully simple forums. Flarum is the next-generation forum software that makes online discussion fun again. ([Source Code](https://github.com/flarum/flarum))

Social Communication Server. ([Source Code](https://github.com/friendica/friendica))

ActivityPub federated social network server implementing the Mastodon client API. ([Source Code](https://codeberg.org/superseriousbusiness/gotosocial))

Bridge that interacts with Fediverse on behalf of your static site. ([Source Code](https://github.com/importantimport/hatsu))

Decentralized identity, privacy, publishing, sharing, cloud storage, and communications/social platform. ([Source Code](https://framagit.org/hubzilla/core))

Flexible kit for private social networks. ([Source Code](https://github.com/humhub/humhub))

Federated microblogging server that communicates over ActivityPub. ([Source Code](https://iceshrimp.dev/iceshrimp/iceshrimp.net))

Lightweight commenting server written in Python and Javascript. It aims to be a drop-in replacement for Disqus. ([Source Code](https://github.com/isso-comments/isso))

Link aggregator for the fediverse (alternative to Reddit). ([Source Code](https://github.com/LemmyNet/lemmy))

Collaborative decision-making tool that makes it easy for anyone to participate in decisions which affect them. ([Source Code](https://github.com/loomio/loomio))

Federated microblogging server. ([Source Code](https://github.com/mastodon/mastodon), [Clients](https://github.com/hyperupcall/awesome-mastodon))

Fully featured modern forum application that is fast, scalable and responsive. ([Source Code](https://github.com/rafalp/Misago))

Decentralized app-like microblogging server/SNS for the Fediverse, using the ActivityPub protocol like GNU social and Mastodon. ([Source Code](https://github.com/misskey-dev/misskey))

Modern, federated social network based on XMPP, with a fully featured group-chat, subscriptions and microblogging. ([Source Code](https://github.com/movim/movim))

Free, extensible forum software package. ([Source Code](https://github.com/mybb/mybb))

Forum software built for the modern web. ([Demo](https://try.nodebb.org/), [Source Code](https://github.com/NodeBB/NodeBB))

Social networking software that allows you to make a social networking website and helps your members build social relationships, with people who share similar professional or personal interests. ([Source Code](https://github.com/opensource-socialnetwork/opensource-socialnetwork))

Flat-forum bulletin board software solution that can be used to stay in touch with a group of people or can power your entire website. ([Source Code](https://github.com/phpbb/phpbb))

Ethical photo sharing platform, powered by ActivityPub federation (alternative to Instagram). ([Source Code](https://github.com/pixelfed/pixelfed))

Federated microblogging server, Mastodon, GNU social, & ActivityPub compatible. ([Source Code](https://git.pleroma.social/pleroma/pleroma))

Q&A-based community knowledge-sharing software. ([Source Code](https://github.com/codidact/qpixel))