GitHub Desktop - GitHub Desktop is a seamless way to contribute to projects on GitHub and GitHub Enterprise.
Documize - Enterprise-grade wiki and knowledge management platform
Git - Git is a free and open source version control system designed to handle everything from small to very large projects with speed and efficiency. It is easy to learn and lightweight with lighting fast performance that outclasses competitors.
HackMD - Fast and flexible, real-time collaborative markdown, inspired by Hackpad.
Mercurial SCM - Mercurial is a free, distributed source control management tool.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.