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.
MacDown - MacDown is an open source Markdown editor for OS X, released under the MIT License.
markdown to web - Convert markdown to online web page
Frost - An open API for Blockchain timestamping
Mochi - Write notes and flashcards with Markdown and study them with spaced repetition.
Typora - A minimal Markdown reading & writing app.