https://moodle.org/

Moodle is a free, online Learning Management system enabling educators to create their own private website filled with dynamic courses that extend learning, anytime, anywhere.

https://docu.ilias.de/ilias.php?baseClass=ilrepositorygui&reloadpublic=1...

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.

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

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

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.