Texy!!

TinyMCE is a platform independent web based Javascript HTML WYSIWYG editor control released as Open Source under LGPL by Moxiecode Systems AB. It has the ability to convert HTML TEXTAREA fields or other HTML elements to editor instances. TinyMCE is very easy to integrate into other CMS systems.

CKEditor is an open source WYSIWYG rich text editor and collaboration solution designed to bring common word processor features directly to web pages, simplifying their content creation.

MWeb can handle professional-level markdown with support for markdown extensions. It provides publishing to various social networks and blogging formats, as well as various preview themes. It also has two work modes: external, which allows the addition of external folders; and library, designed for note-taking and static blogging.

WYMeditor is a web-based WYSIWYM (What You See Is What You Mean) XHTML editor (not WYSIWYG).

Textile is a lightweight markup language originally developed by Dean Allen and billed as a "humane web text generator". Textile converts its marked-up text input to valid, well-formed XHTML and also inserts character entity references for apostrophes, opening and closing single and double quotation marks, ellipses and em dashes.

Introduction

Redactor Text Editor is a WYSIWYG html editor.Redactor provides smooth and clean design, limitless flexibility and extensibility, simple and super-efficient API and amazing user experience.

Docutils is an open-source text processing system for processing plaintext documentation into useful formats, such as HTML, LaTeX, man-pages, open-document or XML. It includes reStructuredText, the easy to read, easy to use, what-you-see-is-what-you-get plaintext markup language.

Finally, a free open source cross-browser WYSIWYG editor thats packed with every rich-text editing feature you need.

React Rich Text Editor is a UI component built completely in React that is meant to be a full-featured textarea replacement. It's based on the excellent, open source Draft.js from Facebook which is performant and production-tested.