Documize - Enterprise-grade wiki and knowledge management platform
AMuseWiki - Amusewiki is more than just a wiki engine, it’s also a powerful authoring, archiving and publishing platform.
HackMD - Fast and flexible, real-time collaborative markdown, inspired by Hackpad.
DokuWiki - DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.
BetterDocs - Create & Manage Knowledge Base Documentation Effectively To Reduce Support Tickets, Increase productivity & User Experience with BetterDocs.