HedgeDoc : HedgeDoc (formerly known as CodiMD) is an open-source, web-based, self-hosted, collaborative markdown editor.
You can use it to easily collaborate on ...
Firepad : Firepad is an open-source, collaborative code and text editor. It is designed to be embedded inside larger web applications.
Mockingbird : Mockingbird is an online tool that makes it easy for you to create, link together, preview, and share mockups of your website or application.
Etherpad is an Open Source online editor providing collaborative editing in really real-time powered by Node.js
