DokuWiki - DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
Nuclino - Nuclino is a unified real-time workspace for teams that brings all your notes, tasks, and docs together in one place.
TiddlyWiki - a non-linear personal web notebook
Confluence - Confluence is content collaboration software that changes how modern teams work
BookStack - An open source knowledge management application that's focused on ease of use.
XWiki - A powerful Open Source collaborative platform enhancing collaboration and communication.