MDView

A tiny native macOS Markdown viewer/editor. 172 KB binary, <1 MB total — no Electron, no runtimes.

• Double-click any .md file → rendered preview (registers as a Markdown editor with Finder)
• Complete GFM rendering: tables, task lists, images, strikethrough, footnotes, syntax-highlighted code blocks
• Edit mode: ⌘E toggles a plain-text editor, ⌘S saves (autosave/recents come from macOS)
• Quick Look extension: spacebar previews and Finder's preview pane render through the same pipeline
• GitHub-style light/dark theme, follows the system appearance
• Opens maximized; quits when the last window closes

Rendering is marked + highlight.js running locally (bundled, zero network at runtime) inside a WKWebView / JavaScriptCore. See THIRD_PARTY_LICENSES.md.

Build

Requires macOS 13+ and the Xcode Command Line Tools (full Xcode not needed).

./build.sh

Produces build/MDView.app (ad-hoc codesigned).

Install

1. Copy build/MDView.app to /Applications and launch it once.
2. Make it the default for Markdown: right-click any .md file → Get Info → Open with → MDView → Change All.
3. Quick Look: if spacebar still shows plain text, enable MDView under System Settings → General → Login Items & Extensions → Quick Look.

Downloaded a prebuilt .app? It is ad-hoc signed, so Gatekeeper will block the first launch: right-click → Open → Open (or xattr -d com.apple.quarantine MDView.app). Building from source avoids this.

Known limits

• Relative-path images render in the app, but not in Quick Look previews (needs QL attachments — noted in code).
• arm64 only as built; Intel needs a rebuild on x86_64.

License

MIT — see LICENSE. Bundled renderer libraries are MIT/BSD, see THIRD_PARTY_LICENSES.md.