Beyond Compare - Beyond Compare allows you to compare files and folders.
NotePlan - Make plans inside an individual markdown note for every day in your calendar. Use it as a journal for your daily tasks and plan todos in advance. For Mac, iPhone and iPad.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
markdown to web - Convert markdown to online web page
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.