TextNut SD is an easy-to-use markdown editor. Whether you are markdown expert, or even if you are not familiar with markdown, TextNut SD gives you an enjoyable writing experience. It's fully compatible with CommonMark, a strongly defined, highly compatible specification of Markdown. And you can publish or save drafts to Medium, WordPress, and Blogger in one click.
Note: The downloadable demo is at 1.0.2. The version available for purchase on the Mac App Store is version 1.0.5.