Twig

Twig is a modern markdown editor for macOS users. Even though it's in the early stages, it supports a good amount of themes, live previews, auto-saving, multiple tab support, exporting options (HTML, PDF), and much more.

Looks like a little bit Sublime Text yet specialized on Markdown. It's also very convenient for Steemit authors to focus on the writing while getting advantage of Markdown.

Also available on Github as an open-source project and distributed under GPL-3.0.