CKEditor - Real-time collaborative future-ready rich text editor
mdbook - Gitbook alternative in Rust
Summernote - Summernote is a JavaScript library that helps users create WYSIWYG editors online.
MkDocs - Project documentation with Markdown.
Froala Editor - Froala Editor is a WYSIWYG HTML editor that enables rich text editing capabilities for the applications.
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.