TextPad - TextPad is a powerful, general purpose editor for plain text files that is easy to use, with all the features a power user requires.
Minimalist Markdown Editor - This is the simplest and slickest Markdown editor.
The Most Dangerous Writing App - If you stop typing, all progress is lost.
Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
Notepin - Extremely simple note-taking + blogging ✍️
Typora - A minimal Markdown reading & writing app.