QuickMD

A lightweight, native macOS Markdown previewer. Double-click any .md file and get a beautifully rendered preview instantly.

Features

• GFM Support — Full GitHub Flavored Markdown (tables, task lists, strikethrough, autolinks)
• Syntax Highlighting — 190+ languages via highlight.js with light/dark themes
• Mermaid Diagrams — Flowcharts, sequence diagrams, Gantt charts, and more
• LaTeX Math — Inline and display math via KaTeX ($...$ and $$...$$)
• Dark Mode — Auto-adapts to system appearance, with manual toggle (Cmd+Shift+D)
• Live Reload — Automatically refreshes when the source file changes
• PDF Export — Export rendered Markdown to PDF (Cmd+Shift+E)
• Table of Contents — Sidebar TOC navigation (Cmd+Shift+T)
• Find in Document — Full-text search with highlighting (Cmd+F)
• Local Images — Relative image paths resolved correctly
• Code Copy — One-click copy button on code blocks
• Zero Dependencies — No Electron, no Node.js runtime needed

Requirements

• macOS 12.0 (Monterey) or later
• Xcode Command Line Tools (xcode-select --install)
• Internet connection (first build only, to download JS libraries)

Build

cd QuickMD
chmod +x build.sh
./build.sh

The app will be built to dist/QuickMD.app.

Install

cp -r dist/QuickMD.app /Applications/

Set as Default Markdown Viewer

1. Right-click any .md file in Finder
2. Select "Get Info"
3. Under "Open With", select "QuickMD"
4. Click "Change All..."

Usage

• Open file: Double-click a .md file, or use File → Open (Cmd+O)
• Reload: Cmd+R (also auto-reloads on file change)
• Toggle dark mode: Cmd+Shift+D
• Toggle TOC sidebar: Cmd+Shift+T
• Find text: Cmd+F
• Export PDF: Cmd+Shift+E
• Print: Cmd+P
• Reveal source: File → Reveal Source File

Keyboard Shortcuts

Shortcut	Action
Cmd+O	Open file
Cmd+R	Reload preview
Cmd+Shift+D	Toggle dark/light mode
Cmd+Shift+T	Toggle TOC sidebar
Cmd+F	Find in document
Cmd+G	Find next
Cmd+Shift+G	Find previous
Cmd+Shift+E	Export as PDF
Cmd+P	Print
Cmd+W	Close window
Cmd+Q	Quit

Architecture

QuickMD.app/
├── Contents/
│   ├── Info.plist
│   ├── MacOS/
│   │   └── QuickMD          (native Obj-C binary)
│   └── Resources/
│       ├── QuickMDRenderer.sh (HTML generator)
│       ├── viewer.css         (styles)
│       ├── viewer.js          (rendering logic)
│       └── vendor/            (JS libraries)
│           ├── marked.umd.js
│           ├── purify.min.js
│           ├── mermaid.min.js
│           ├── katex.min.js
│           ├── katex.min.css
│           ├── katex-auto-render.min.js
│           ├── fonts/
│           └── highlight/
│               ├── highlight.min.js
│               ├── github.min.css
│               └── github-dark.min.css

How It Works

1. Native Objective-C app opens .md files
2. Shell script reads the Markdown, base64-encodes it into an HTML template
3. WKWebView loads the HTML with bundled JS libraries
4. marked.js parses Markdown → HTML
5. DOMPurify sanitizes the output
6. highlight.js adds syntax highlighting
7. Mermaid renders diagrams
8. KaTeX renders math formulas
9. FSEvents watches for file changes and auto-reloads

License

MIT