DokuWiki - DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
MkDocs - Project documentation with Markdown.
TiddlyWiki - a non-linear personal web notebook
Docusaurus - Easy to maintain open source documentation websites