Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.
GitHub Team Discussions - Now there's more space to talk through your projects 💬
GraphJS - Make any website social
gUmi - Manage infinite Git profiles in one click
Circle.so - Bring together your discussions, memberships, and content. Integrate a thriving community wherever your audience is, all under your own brand.
Refactor.io - Share your code instantly for refactoring and code review