- [Buddycloud](http://buddycloud.com/) - Tools, libraries, services and a community to build user-to-user, group and social messaging into your app. Saves time. Scales up. Supports you. ([Source Code](https://github.com/buddycloud)) `Apache-2.0``Java`
- [BuddyPress](https://buddypress.org/about/) - Powerful plugin that takes your WordPress.org powered site beyond the blog with social-network features like user profiles, activity streams, user groups, and more. ([Source Code](https://buddypress.svn.wordpress.org/trunk/)) `GPL-2.0``PHP`
- [cartulary](https://github.com/daveajones/cartulary) - RSS reader, readability tool, article archiver, microblogger, social graph manager and reading list manager. `CDDL-1.0``PHP`
- [Commento](https://gitlab.com/commento/commento-ce) - Commento is a discussion platform that you can embed on your blog, news articles, and any place where you want your readers to add comments. `MIT``GO`
- [Discourse](http://www.discourse.org/) - Advanced forum / community solution based on Ruby and JS. ([Demo](https://try.discourse.org/), [Source Code](https://github.com/discourse/discourse)) `GPL-2.0``Ruby`