wysihtml5 : an open source rich text editor based on HTML5 technology and the progressive-enhancement approach.
NicEdit : WYSIWYG Content Editor, Inline Rich Text Application
Slate : Slate is a completely customizable framework for building rich text editors.
Slate lets you build rich, intuitive editors like those in Medium, Dropbo...
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 ...
fuelux : Extends Twitter Bootstrap with additional lightweight JavaScript controls. Easy to install, customize, update, and optimize. All functionality covered...
CKEditor is an open source WYSIWYG text editor designed to bring common word processor features directly to web pages, simplifying their content creation. Its core code is written in JavaScript.