MarsDawn

Built out of the Mac's own parts.

MarsDawn is a native Mac app for reading and reviewing Markdown, with live split preview, Mermaid diagrams, KaTeX math, Quick Look and PDF export, free to try for 14 days and USD 4.99 once to unlock.

The windows, tabs, menus and text editor are the Mac's own. The rendered page is drawn by WebKit, the engine behind Safari.

MarsDawn in split view: the Markdown source on the left, the rendered page on the right.
In this screenshot
  1. A native Mac window.
  2. The Mac's text editor, with Markdown highlighting.
  3. ⌘1 source, ⌘2 split, ⌘3 preview.
  4. The page updates as you type.

What that means

Editing

The rest of the Mac