CKEditor - Real-time collaborative future-ready rich text editor
TinyMCE - TinyMCE is a content editor that functions as a plug-in for Wordpress websites.
Trumbowyg - Feature-packed WYSIWYG editor in only 15kB of JavaScript
Editor.js - A block-styled editor with clean JSON output
Summernote - Summernote is a JavaScript library that helps users create WYSIWYG editors online.
Redactor Text Editor - WYSIWYG html editor.