Paste to Markdown

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

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Features

• 📐 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.

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How to Use

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.

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Project Structure

Paste-to-Markdown/
├── index.html                   # Main entry point, layout, and styling
├── Makefile                     # Local server management and syntax check tasks
├── 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)

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Local Development

No build tools, npm packages, or bundlers are required. 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

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Credits

• 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.

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License

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