Mark My Words is a free and open-source tool for previewing Markdown markup as it is written. Unlike traditional Markdown editors, Mark My Words is designed to be used with an external text editor.
To use Mark My Words, open it and browse to a target Markdown file. Mark My Words will poll the target file for changes every 0.5 seconds, and re-render it if changes are found.
The project is written in C#, with the .Net 4.0 framework.