CKEditor - Real-time collaborative future-ready rich text editor
SCEditor - A lightweight WYSIWYG BBCode & HTML editor
Redactor Text Editor - WYSIWYG html editor.
TinyMCE - TinyMCE is a content editor that functions as a plug-in for Wordpress websites.
PHP Markdown - PHP port of the Markdown text-to-HTML conversion tool for web writers.
ContentTools - A small & beautiful WYSIWYG editor for HTML content.