BuddyPress!

Diaspora is a federated social networking service, designed to be a more privacy-aware alternative to Facebook . Share what you want, with whom you want.

Friendica is a distributed social network application which runs on commodity hosting platforms - PHP/MySQL/Apache. (If you can install Drupal or Wordpress you can probably install Friendica)

HumHub is a free social network software and framework built to give you the tools to make teamwork easy and successful.

Hubzilla is a powerful platform for creating interconnected based websites featuring a decentralized identity, communications, and permissions framework built using common webserver technology. Hubzilla is very suitable for communities (of any size).

Our philosophy is that your data are yours and you must always be in control. Movim achieves this through a complete decentralisation of users' data and accounts.

Ello is a simple, beautiful, and ad-free social network created by a small group of artists and designers.

Libertree is free, libre, open-source software which is intended to provide a way for people to create their own social network. Libertree social networks can be free from commercial influence and manifestation, such as behaviour tracking, user profiling, advertising, data mining and analysis, and covert information filtering.

Buddycloud is built for people who care about their privacy.