Markdown Live Previewer
Draft, preview, and refine your documentation instantly.
Editor
Preview
Drafting a README, writing documentation, or composing a blog post in Markdown? Type in the editor and see the rendered output update instantly in the preview pane — with full GitHub Flavored Markdown support.
Last Updated: April 8, 2025Privacy: 100% Local Browser Processing
What is the Markdown Previewer?
The Markdown Live Previewer is a dual-pane editor that converts Markdown syntax into formatted HTML in real time. Markdown is the de facto standard for documentation, README files, technical writing, and content management systems. This tool supports GitHub Flavored Markdown (GFM), including tables, task lists, strikethrough, fenced code blocks, and auto-linked URLs.
Real-World Use Cases
- README authoring — write and preview README.md files for GitHub repositories with instant visual feedback on formatting.
- Technical documentation — draft documentation for developer portals, wikis, or knowledge bases using Markdown.
- Blog content — compose articles in Markdown for static site generators (Hugo, Jekyll, Gatsby, Next.js) with live preview.
- Note-taking — quickly format meeting notes, code review comments, or learning notes with proper headings, lists, and code blocks.
How to Use
- 1Type or paste your Markdown code into the left editor pane.
- 2See the formatted result instantly in the right preview pane.
- 3Toggle between Split and Full-Preview modes.
- 4Copy the raw Markdown or download the result.
Technical Deep Dive
Markdown parsing is implemented using the 'marked' library, a high-performance GFM-compliant parser that converts Markdown source text into HTML. The parser processes the input in two phases: first, it tokenizes the source into a stream of block-level tokens (headings, paragraphs, lists, code blocks, tables) and inline tokens (bold, italic, links, images). Then, it renders each token into the corresponding HTML elements. Security is critical in any HTML rendering pipeline — malicious Markdown could contain embedded HTML with JavaScript (XSS attacks). This tool mitigates this risk using DOMPurify, a DOM-only XSS sanitizer that strips dangerous HTML elements and attributes from the rendered output. The sanitization happens after Markdown-to-HTML conversion, ensuring that only safe HTML reaches the preview pane. The split-pane layout provides simultaneous editing and preview, with scroll synchronization so the preview tracks your editing position.
Pro Tips & Best Practices
- Use fenced code blocks (triple backticks) with a language identifier for syntax-highlighted code samples: ```javascript
- The preview uses GitHub-style CSS, so your content will look very similar to how it appears on GitHub, GitLab, or similar platforms.
- Use horizontal rules (---) to create visual section breaks in long documents.
- Remember that Markdown requires a blank line before lists and code blocks to render correctly.