DokuWiki - DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
Dr.Explain - Dr.Explain software is a help file authoring tool.
Wiki.js - An open source, modern and powerful wiki app built on Node.js, Git, and Markdown.
WinCHM - Creating CHM file, Make CHM file, Web Help. WinCHM Pro - Help authoring software (CHM, WebHelp, DOC, PDF) . With this powerful tool you can not only create chm file from scratch, but also convert a set of existing HTML files to a chm file.
TiddlyWiki - a non-linear personal web notebook
Document360 - Self-service knowledge base software focused on SaaS Products & Enterprise Software Projects.