MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
Confluence - Confluence is content collaboration software that changes how modern teams work
TiddlyWiki - a non-linear personal web notebook
Wiki.js - An open source, modern and powerful wiki app built on Node.js, Git, and Markdown.
Nuclino - Nuclino works like a collective brain, helping teams bring all their knowledge, docs, and projects together in one place. It's a modern, simple, and blazingly fast way to collaborate.
BookStack - An open source knowledge management application that's focused on ease of use.