Forums

http://www.bndlg.de/~jonny/projects/wboard/index.html

WBoard allows you to run several WWWBoard-style forums on your website. Messages are stored in 3 tables and are searchable.

http://www.viscacha.org/

https://vanillaforums.com/en/software/

Simple and flexible forum software. Great for enthusiasts and small businesses.

http://newsboard.unclassified.de/

https://simplemachines.org/

Elegant. Effective. Powerful. Free. SMF is all of the above. SMF is a next-generation community software package and is jam-packed with features, while at the same time having a minimal impact on resources.

https://punbb.informer.com/

PunBB is a fast and lightweight PHP-powered discussion board.

http://phpforum.sourceforge.net/

PHPForum is optimized to provide programmers with a forum who is easy and fast to install. Easy modification is also a feature as all HTML are separated in templates

https://www.phpbb.com/

phpBB is a free flat-forum bulletin board software solution that can be used to stay in touch with a group of people or can power your entire website.

https://www.phorum.org/

https://mybb.com/

MyBB is the free and open source, intuitive, extensible, and incredibly powerful forum software you've been looking for.