Raneto - Open source, flat-file Knowledgebase platform that uses static Markdown files
Documize - Enterprise-grade wiki and knowledge management platform
HowHive - Knowledgebases for teams and companies of all sizes. Knowledge sharing and finding made simple.
HackMD - Fast and flexible, real-time collaborative markdown, inspired by Hackpad.
Obsidian.md - A second brain, for you, forever. Obsidian is a powerful knowledge base that works on top of a local folder of plain text Markdown files.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.