MarkdownPreview

A macOS Quick Look extension that renders Markdown files with GitHub-style formatting directly in Finder.

Features

• Preview .md files in Finder with Space key
• GitHub-style CSS rendering
• Dark mode support
• Headings, bold, italic, links, images
• Code blocks with syntax highlighting classes
• Tables, blockquotes, lists
• Horizontal rules

Installation

Homebrew

brew tap danhloc112/tap
brew install --cask markdown-preview

From DMG

1. Download MarkdownPreview.dmg from Releases
2. Open the DMG and drag MarkdownPreview.app to Applications
3. Launch the app once to register the Quick Look extension
4. Go to System Settings > General > Login Items & Extensions > Quick Look and enable MarkdownPreviewExtension
5. Select any .md file in Finder and press Space to preview

From source

git clone https://github.com/danhloc112/markdown-preview.git
cd markdown-preview
brew install xcodegen  # if not installed
xcodegen generate
xcodebuild archive -scheme MarkdownPreview -destination "platform=macOS" \
  -archivePath build/MarkdownPreview.xcarchive \
  CODE_SIGN_IDENTITY="-" CODE_SIGNING_ALLOWED=YES
cp -R build/MarkdownPreview.xcarchive/Products/Applications/MarkdownPreview.app /Applications/

Requirements

• macOS 12.0 or later
• Xcode 15+ (for building from source)

Tech Stack

• swift-markdown — Apple's Markdown parser (AST-based)
• NSAttributedString — HTML rendering in Quick Look sandbox
• XcodeGen — Project generation from project.yml

Project Structure

MarkdownPreview/
├── MarkdownPreview/              # Host app
│   ├── AppDelegate.swift
│   └── Assets.xcassets/          # App icon
├── MarkdownPreviewExtension/     # Quick Look extension
│   ├── PreviewViewController.swift
│   ├── MarkdownParser.swift      # Markdown → HTML converter
│   ├── Resources/
│   │   └── template.html         # GitHub-style HTML template
│   └── Info.plist
├── MarkdownPreviewTests/         # Unit tests
│   └── MarkdownParserTests.swift
└── project.yml                   # XcodeGen config

Troubleshooting

If Quick Look preview doesn't show up:

# Reset Quick Look
qlmanage -r

# Restart Finder
killall Finder

# Verify extension is registered
pluginkit -mA | grep MarkdownPreview

Make sure the extension is enabled in System Settings > General > Login Items & Extensions > Quick Look.

License

MIT