Using Opus 4.6 I built a markdown viewer for macOS that uses zero web technology. No Electron, no WebView — markdown is parsed with cmark-gfm and rendered directly to NSAttributedString via TextKit 2. The result is native text selection, native accessibility, and a ~1MB binary that launches pretty much instantly. It supports GFM tables, task lists, syntax-highlighted code blocks, and inline images. You get a built-in themes (Solarized, Dracula, GitHub, Monokai) plus the ability to import your own from iTerm2 or VS Code theme files.

The part I’m most pleased with is the Quick Look integration — select a .md file in Finder, hit Space, and you get a fully themed preview using whatever theme and fonts you’ve configured in the app. No setup required; the QL extension registers automatically on first launch. It also bundles variable fonts (Geist, Inter, JetBrains Mono, iA Writer Mono, and more) so typography looks good out of the box.

The whole thing is built in Swift with no dependencies beyond cmark-gfm and Highlightr.

https://github.com/jahala/mrkd