Paste to Markdown

A fast, private, and client-side web application for converting clipboard content (HTML, RTF, and plain text) into clean, standard Markdown.

• 📐 LaTeX & Math Expressions Support

  • Converts math formulas from clipboard HTML into standard Markdown syntax:
    • Inline math: $...$
    • Block math: $$...$$ and math code blocks
  • Intelligently extracts TeX source from:
    • KaTeX HTML (<annotation encoding="application/x-tex">)
    • MathML (<math>) and <annotation> tags
    • MathJax containers (<mjx-container>) and script elements
    • Wikipedia math formula images (alt attribute containing TeX)
    • Custom HTML data attributes (data-tex, data-formula, data-latex)
  • Built-in offline KaTeX rendering in the Preview tab with zero external network requests.

• 📋 Universal Multi-Source Clipboard Conversion

  • Seamlessly handles rich text copied from:
    • Web browsers (tables, nested lists, headings, blockquotes)
    • Microsoft Word, Outlook, and Office RTF content (cleans up bullet artifacts and spacing)
    • Microsoft Excel spreadsheets (converts to GFM Markdown tables with multiline cell support)
    • VS Code and code editors (preserves indentation and strips redundant margins)
    • Plain text output (such as GitHub Copilot CLI or terminal logs)

• 📑 Dual-Format (MIME) Clipboard Copy

  • Dedicated 📋 Copy button writes both text/plain (raw Markdown) and text/html (rendered HTML) to the system clipboard simultaneously.
  • Paste into Markdown/code editors to get raw Markdown, or paste directly into rich text editors (Notion, Google Docs, Word, Slack, Teams) with formatting preserved.

• 🔗 One-Click Shareable Links

  • Use the 🔗 Share button to compress and encode your converted Markdown directly into the URL hash.
  • Recipients can open the link to instantly read, preview, or copy the content without requiring any server database or account.

• 👀 Live Real-Time Preview

  • Side-by-side or tabbed Edit and Preview modes with GitHub Flavored Markdown (GFM) tables, syntax rendering, and KaTeX mathematical equation support.

• 🌓 Theme Switcher

  • Choose between System default, Light, and Dark modes.
  • Saves your theme preference in local storage with automatic contrast adjustment.

• 🌍 Multi-Language Support (15 Languages)

  • Fully translated interface available in:
    • English, 繁體中文, 简体中文, 日本語, 한국어, Español, Français, Português, Русский, العربية (with native RTL support), Türkçe, Tiếng Việt, ภาษาไทย, Bahasa Indonesia, and हिन्दी.

• 🔒 Privacy & Security

  • 100% Client-Side: All parsing, sanitization, and rendering execute entirely within your browser sandbox. No telemetry, no backend server, and no clipboard data is ever sent to the network.
  • Strict HTML sanitization via DOMParser blocking malicious scripts, unsafe URLs, and protocol injection.

1. Copy formatted content from any webpage, document, or application (Ctrl+C or ⌘+C).
2. Paste onto the Paste to Markdown window (Ctrl+V or ⌘+V).
3. The content is instantly converted into Markdown:
   • Click 📋 Copy to copy both Markdown and formatted HTML to your clipboard.
   • Click 🔗 Share to generate a shareable URL containing the document.
4. Keyboard Shortcuts:
   • Escape: Clear workspace and reset.
   • Alt+1 / Option+1: Switch to Edit tab.
   • Alt+2 / Option+2: Switch to Preview tab.

Paste-to-Markdown/
├── index.html                   # Main entry point, layout, and styling
├── Makefile                     # Local server management, syntax check, and test tasks
├── package.json                 # Dev-only dependencies for the E2E tests (the app needs none)
├── playwright.config.js         # Playwright E2E test configuration
├── assets/
│   ├── clipboard2markdown.js    # Core app logic, clipboard handling, and KaTeX extensions
│   ├── to-markdown.js           # Custom HTML-to-Markdown conversion utilities
│   ├── bootstrap.css            # Base UI stylesheet
│   ├── workspace-bg-light.png   # Light theme background asset
│   └── workspace-bg-dark.png    # Dark theme background asset
├── vendor/
│   ├── turndown/                # Turndown HTML-to-Markdown converter
│   ├── turndown-plugin-gfm/     # GFM table and task list plugin
│   ├── marked/                  # Markdown parser and renderer
│   └── katex/                   # Local offline KaTeX library, fonts, and stylesheets
├── i18n/                        # Localization dictionaries (15 languages)
├── e2e/                         # Playwright end-to-end tests and coverage tooling
├── tests/                       # Golden HTML-to-Markdown fixtures used by the E2E tests
└── .github/workflows/e2e.yml    # Runs the E2E tests and coverage gate on every pull request

No build tools, npm packages, or bundlers are required to run the app. You can serve the project using any static web server:

# Start local server and automatically open the browser
make

# Or start the server in the background
make serve-bg

# Check background server status
make status

# Stop background server
make stop

# Verify JavaScript syntax
make check

The E2E tests use Playwright with Chromium and measure JavaScript coverage of the app's own code (assets/clipboard2markdown.js, assets/to-markdown.js, i18n/*.js, and the inline scripts in index.html; vendor libraries are excluded). Node.js 22.12 or later is required for the tests only.

# Install test dependencies and the Chromium browser (first time only)
npm install
npx playwright install chromium

# Run all E2E tests
npm test

# Run all E2E tests and fail if coverage is below 90% (lines, statements, functions)
npm run test:coverage

# Run a single spec file
npx playwright test e2e/convert-core.spec.js

# List uncovered lines of a file from the last run
node e2e/support/uncovered.js clipboard2markdown

The coverage report is written to coverage/ (open coverage/index.html). Every pull request runs npm run test:coverage in GitHub Actions.

• Based on to-markdown by Dom Christie.
• Markdown conversion powered by Turndown and Marked.
• Math rendering powered by KaTeX.
• Designed, developed, and maintained by Will 保哥的技術交流中心.

This project is open source and available under the MIT License.