Vanilla Forums - Build an engaging community forum using Vanilla's modern cloud forum software.
Gab - Gab is an ad-free social network dedicated to free speech.
Forumbee - Forumbee offers community forums for discussions, feedback and Q&A.
Friendica - Decentralisation - Privacy - Interoperability
Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.
Mastodon - Mastodon is a decentralized, open source social network. This is just one part of the network, run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome!