MarkView

Native macOS markdown preview with MCP server for Claude Code. Claude writes markdown — MarkView renders it live, in a real native window, while you work.

Versions: The macOS app (app badge) and the npm MCP wrapper (npm badge) are versioned independently. App releases happen when the Swift binary changes; npm patches happen for MCP server improvements. Both badges always show the latest of each.

Quick Start — Claude Code

One command to wire MarkView into every Claude Code session:

claude mcp add --transport stdio --scope user markview -- npx mcp-server-markview

That's it. Claude can now call preview_markdown to render any markdown string in a native macOS window, or open_file to open any .md file directly.

Claude Desktop Setup

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "markview": {
      "command": "npx",
      "args": ["mcp-server-markview"]
    }
  }
}

Note: MCP servers belong in ~/.claude.json (Claude Code) or claude_desktop_config.json (Claude Desktop), not ~/.claude/settings.json.

Installation

Homebrew (recommended)

# Full .app with Quick Look extension — Apple notarized, Gatekeeper approved
brew install --cask paulhkang94/markview/markview

# CLI only (builds from source)
brew tap paulhkang94/markview
brew install markview

Build from source

Prerequisites: macOS 14+, Swift 6.0+ (Xcode Command Line Tools)

git clone https://github.com/paulhkang94/markview.git
cd markview
swift build -c release

Install as app (Open With support)

bash scripts/bundle.sh --install

Creates MarkView.app in /Applications and registers it with Launch Services for right-click > Open With in Finder.

Install CLI

bash scripts/install-cli.sh

Creates mdpreview and md symlinks in ~/.local/bin/.

Usage

CLI

mdpreview README.md       # Open a file
mdpreview                 # Open empty editor

Finder

Right-click any .md, .markdown, .mdown, .mkd file > Open With > MarkView

Programmatic

open -a MarkView README.md

Features

• GitHub Flavored Markdown via swift-cmark (tables, strikethrough, autolinks, task lists, footnotes)

• Mermaid diagrams — flowcharts, sequence, Gantt, ER, and pie charts

• Syntax highlighting via Prism.js (18 languages)

• Quick Look integration — spacebar-preview .md files in Finder without opening the app

• Markdown linting with 9 built-in rules and status bar diagnostics

• Live split-pane editor with WKWebView rendering and bidirectional scroll sync

• File watching with DispatchSource — works with VS Code, Vim, and other editors

• Local image rendering — inlines relative paths like ![](./image.png) correctly

• Export to HTML and PDF

• HTML sanitizer — strips scripts, event handlers, and XSS vectors

• Drag and drop — drop any .md file onto the window to open

• Find & Replace — Cmd+F / Cmd+Option+F

• Format on save — auto-applies lint fixes

• Auto-save, word count, line numbers, scroll position preservation

• Dark mode — system/light/dark theme options, 18 configurable settings

Architecture

Sources/MarkViewCore/           # Library (no UI, fully testable)
  MarkdownRenderer.swift        # cmark-gfm C API wrapper
  FileWatcher.swift             # DispatchSource file monitoring
  MarkdownLinter.swift          # 9-rule pure Swift linting engine
  HTMLSanitizer.swift           # XSS prevention
  LanguagePlugin.swift          # Plugin protocol + registry
  Plugins/                      # CSV, HTML, Markdown plugins

Sources/MarkView/               # SwiftUI app (macOS 14+)
  ContentView.swift             # Split-pane editor + preview
  WebPreviewView.swift          # WKWebView with Prism.js
  ExportManager.swift           # HTML/PDF export

Sources/MarkViewMCPServer/      # MCP server for AI tool integration
  main.swift                    # stdio JSON-RPC (preview_markdown, open_file)

Tests/TestRunner/               # 403 standalone tests (no XCTest)
Tests/VisualTester/             # 5 visual regression tests + WCAG contrast
Tests/FuzzTester/               # 10K random input crash testing
Tests/DiffTester/               # Differential testing vs cmark-gfm CLI

See docs/ARCHITECTURE.md for full details.

Testing

swift run MarkViewTestRunner    # 403 tests
python3 scripts/verify.py       # Full verification (build + tests, writes stamp)
python3 scripts/verify.py --extended  # + fuzz + differential
bash scripts/test-mcp.sh        # MCP protocol tests

Development

swift build
swift run MarkView
swift run MarkView /path/to/file.md

Support

• GitHub Sponsors

• Star this repo to help others find it

License

MIT — see LICENSE.