NodeBB
NodeBB is next-generation forum software - powerful, mobile-ready and easy to use.
Discourse
Discourse is an open-source discussion platform built for the next decade of the Internet.
Photon
A replacement for Lemmy-ui with more features, a better design, and more customizability. It includes Photon UI + Lemmy
HumHub
HumHub to communicate and collaborate, share information, interact with all people in your organization, and personalize the software to fit your individual needs.
AzuraCast
A self-hosted web radio management suite
Mastodon
Mastodon is a free fediverse, open-source social network server with OpenSearch for indexing.
Flarum
Flarum is a delightfully simple discussion platform for your website
Element
Create your community based on Matrix protocol
Owncast
Owncast is a free and open source live video and web chat server for use with existing popular broadcasting software.
Picoshare
PicoShare is a service for sharing images, videos, and other files.
Friendica
A Decentralized Social Network, you can use to host your own social media server that forms one part of the fediverse, an interconnected and decentralized network of independently operated servers
Lemmy
Open-source Reddit alternative. Create your own discussion platform with Lemmy
KBIN
A reddit-like content aggregator and micro-blogging platform for the fediverse.
Lobsters
Lobsters are a computing-focused community centered around link aggregation and discussion.
PhpBB
phpBB is a free 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.
Answer
An open-source knowledge-based community software. You can use it quickly to build Q&A community for your products, customers, teams, and more.