Quikdown is a small, secure markdown parser with bidirectional conversion. Zero dependencies, XSS protection built-in, extensible via plugins for code highlighting and diagrams, and works in browser and Node.js.

For small and fast projects quikdown includes built-in inline styles for a "batteries included" rendering experience, but these can be overridden with themed css (see light and dark examples).

• quikdown.js (9.0KB) - Markdown to HTML Parser with theme support, XSS protection, fence callbacks
• quikdown_bd.js (13.8KB) - Bidirectional (HTML ↔ Markdown) Parser
• quikdown_edit.js (68.0KB) - Drop-in editor component with live preview, copy-as-rich-text, and lazy-loaded fence handlers

🚀 Live Demo | Editor Demo | Documentation

📍 Quick Links: Installation • Quick Start • API • TypeScript • Plugins • Examples

• 📦 Zero dependencies - No external libraries required
• 🌐 Universal - Works in browsers and Node.js
• 🚀 Lightweight - 9.0KB (core), 13.8KB (bidirectional), 68.0KB (editor)
• 🔒 Secure by default - Built-in XSS protection with URL sanitization
• 🎨 Flexible styling - Inline styles or CSS classes with theme support
• 🔌 Plugin system - Extensible fence block handlers
• ⚡ Fast - Optimized regex-based parsing
• 📝 CommonMark subset - Essential markdown features
• ✅ Task Lists - GitHub-style checkboxes
• 🔗 Autolinks - Automatic URL detection
• 🔄 Bidirectional - Convert HTML back to Markdown (quikdown_bd)
• 💬 Lazy linefeeds - Single newlines become line breaks (configurable)
• 📱 Editor component - Drop-in markdown editor with live preview

Quikdown is available via NPM and related unpkg and jsdelivr

npm install quikdown

CDN (ES Modules):

<script type="module">
  import quikdown from 'https://unpkg.com/quikdown/dist/quikdown.esm.min.js';
  document.body.innerHTML = quikdown('# Hello World');
</script>

CDN (UMD):

<script src="https://unpkg.com/quikdown/dist/quikdown.umd.min.js"></script>
<script>
  document.body.innerHTML = quikdown('# Hello World');
</script>

Quikdown is built in 3 versions. The smallest (quikdown) provides markdown to html conversion only. The next (quikdown_bd) provides markdown to html and html to markdown support. The lightweight editor quikdown_edit allows a bidirectional editor with lazy loading for common fences such as codeblocks, svg, and mermaid diagrams is also provided.

// Basic conversion
const html = quikdown('# Hello World',
    {inline_styles: true}  // Use inline styles,  more options in API docs
);

document.body.innerHTML = html;

// Convert with source tracking
const htmlString = quikdown_bd(markdown, options);

// Convert HTML back to Markdown
const markdown = quikdown_bd.toMarkdown(htmlString);

Note: quikdown does not provide a generic html to markdown conversion but uses special tags and limited DOM parsing for HTML to markdown conversion. Standard markdown components such as headings, text styles, tables, quotes, etc are supported. For custom fences quikdown relies on its tag system or 3rd party handlers to provide reverse (html to md) conversion.

const editor = new QuikdownEditor('#container', {
  mode: 'split',           // 'source', 'split', 'preview' 
  theme: 'auto',           // 'light', 'dark', 'auto'
  plugins: { highlightjs: true, mermaid: true } // built-in fence handlers, see API docs for custom plugins
});

editor.setMarkdown('# Content  \nTo be quik or not to be.');  // provide default content
const content = editor.getMarkdown(); // get source content, see APIs for getting / setting HTML 

Note: The editor automatically lazy-loads plugin libraries from CDNs when needed:

• highlight.js - Loaded when code blocks are encountered and highlightjs: true
• mermaid - Loaded when mermaid diagrams are found and mermaid: true
• DOMPurify - Loaded when HTML fence blocks are rendered
• KaTeX - Loaded when math/tex fence blocks are encountered

This keeps the initial bundle small while providing rich functionality on-demand.

quikdown supports built-in styles for a "batteries included" experience or you can bring your own CSS themes. Example css files are provided for basic light and dark themes to get started.

const html = quikdown(markdown, {
  lazy_linefeeds: true,    // Single newlines become <br>
  inline_styles: false,    // Use class based CSS instead of inline styles
  fence_plugin: {          // Custom code block processor (v1.1.0+ API)
    render: myHandler      // Function to render fence blocks
  }
});

Inline styles: All formatting uses inline CSS

quikdown('**bold**', { inline_styles: true });
// <strong style="font-weight: bold;">bold</strong>

Class-based styling: Uses CSS classes (default)

quikdown('**bold**');
// <strong>bold</strong>
// Requires CSS: .quikdown strong { font-weight: bold; }
// see included dist/quikdown.light.css or quikdown.dark.css

Quikdown provides a callback for all fenced text such as code blocks, math, svg etc.

Handle code blocks with custom languages:

const fencePlugin = {
  render: (code, language) => {
    if (language === 'mermaid') {
      // Process with mermaid library and return rendered diagram
      const id = 'mermaid-' + Math.random().toString(36).substr(2, 9);
      setTimeout(() => mermaid.render(id + '-svg', code).then(result => {
        document.getElementById(id).innerHTML = result.svg;
      }), 0);
      return `<div id="${id}" class="mermaid">Loading diagram...</div>`;
    }
    // Return undefined for default handling
  }
};

const html = quikdown(markdown, { fence_plugin: fencePlugin });

quikdown includes TypeScript definitions for better IDE support and type safety:

import quikdown, { QuikdownOptions, FencePlugin } from 'quikdown';

const fencePlugin: FencePlugin = {
  render: (content: string, language: string) => {
    return `<pre class="hljs ${language}">${content}</pre>`;
  }
};

const options: QuikdownOptions = {
  inline_styles: true,
  fence_plugin: fencePlugin
};

const html: string = quikdown(markdown, options);

Text formatting: **bold**, *italic*, ~~strikethrough~~, `code`

Headings: # H1 through ###### H6

Lists:

• Unordered lists

1. Ordered lists

• Task lists

Links: [text](url) and automatic URL detection

Code blocks:

console.log('syntax highlighting support via plugins');

Tables, blockquotes, horizontal rules - See documentation for complete syntax reference

For complete API documentation, see docs/api-reference.md

All HTML is escaped by default. Only safe markdown constructs become HTML:

const unsafe = '<script>alert("XSS")</script> **bold**';
const safe = quikdown(unsafe);
// &lt;script&gt;alert("XSS")&lt;/script&gt; <strong>bold</strong>

Works with React, Vue, Svelte, Angular. See Framework Integration Guide for examples.

For size and security, quikdown doesn't support:

• Reference-style links
• Footnotes
• Definition lists

Note that raw html, svg, etc can be rendered using appropriate fences

<h1>My HTML Content</h1>
<p>Some HTML</p>

as long as an appropriate fence plugin is provided. See API docs for example or try out in quikdown_edit.js which has built-in support for HTML with XSS prevention.

BSD 2-Clause - see LICENSE.txt

• Inspired by the simplicity of early markdown parsers
• Built for the QuikChat project
• CommonMark spec for markdown standardization

• 📖 Documentation
• 🐛 Issues
• 📦 Examples