Simple Machines Forum - Simple Machines offers free open source software such as SMF, the powerful and easy to use community forum written in PHP. Start interesting discussions on your website!
NationBuilder - The world's first platform for leaders, handcrafted from scratch to help you grow your community and lead them to action.
Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.
Crowded Communities - The all-in-one community platform.
phpBB - Raspberry Pi. The Raspberry Pi is a cheap, credit-card sized computer. The official website uses phpBB for their discussion forums. phpBB is not affiliated with nor responsible for any of the sites listed on the showcase.
Ning - Ning is the social platform for the worlds interests and passions online.