EpicEditor is an embeddable JavaScript Markdown editor with split fullscreen editing, live previewing, automatic draft saving, offline support, and more. For developers, it offers a robust API, can be easily themed, and allows you to swap out the bundled Markdown parser with anything you throw at it.

EpicEditor is set up to allow you to use any parser that accepts and returns a string. This means you can use any flavor of Markdown, process Textile, or even create a simple HTML editor/previewer. Theming is easy in EpicEditor as well.

Requirements: JavaScript Framework
Demo: http://oscargodson.github.com/EpicEditor/
License: License Free