Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
CKEditor - Real-time collaborative future-ready rich text editor
Asciidoctor - In the spirit of free software, everyone is encouraged to help improve this project.
TinyMCE - TinyMCE is a content editor that functions as a plug-in for Wordpress websites.
pandoc - Pandoc is a Haskell library for converting from one markup format to another, and a command-line...
Summernote - Summernote is a JavaScript library that helps users create WYSIWYG editors online.