Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.
Disciple - Grow, engage and monetise your community with Disciple community software. Get your own branded community platform on Web, iOS and Android
XenForo - Intuitive. Social. Engaging. Fast. XenForo brings a fresh outlook to forum software.
Proboards - ProBoards is a host of free forums with customer service.
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.
Forumotion.com - Create a free forum : free forum hosting, free forum skins, templates editing, chatbox, RPG mod... Choose PhpBB 2 - 3, Invision or PunBB. Create forums now!