DokuWiki - DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
Dozuki - Dozuki is a web-based tool for creating and distributing step-by-step documentation.
Wiki.js - An open source, modern and powerful wiki app built on Node.js, Git, and Markdown.
REWO - REWO is a knowledge documentation and distribution solution, which drastically improves capturing, visualizing and communicating knowledge.
TiddlyWiki - a non-linear personal web notebook
Bloomfire - Let Bloomfire help you get organized! Organize your content, build your company knowledge base and help your employees to be more successful.