CKEditor : CKEditor is an open source WYSIWYG text editor designed to bring common word processor features directly to web pages, simplifying their content creat...
mmm.page : Dead simple, drag & drop personal websites.
Strut : An HTML5 Presentation Editor. A GUI / Authoring Tool for ImpressJS and Bespoke.js
Source at https://github.com/tantaman/Strut
Xinha : Xinha is a powerful WYSIWYG HTML editor component that works in all current browsers. Its configurabilty and extensibility make it easy to build just ...
NicEdit : WYSIWYG Content Editor, Inline Rich Text Application
an open source rich text editor based on HTML5 technology and the progressive-enhancement approach.
