Markdown to HTML in 2026: Libraries, Security, and Performance

Markdown is the lingua franca of developer documentation. But when it hits the browser, it needs to become HTML. Here's how to do it safely and efficiently in 2026. Quick Conversion JavaScript (marked) import { marked } from ' marked ' ; const html = marked ( ' # Hello **World** ' ); Python import markdown html = markdown . markdown ( text , extensions = [ ' tables ' , ' fenced_code ' ]) Command Line pandoc README.md -o output.html pandoc -f gfm README.md -o output.html --standalone JavaScript Library Comparison Library Size Speed GFM Extensible marked 32KB Very fast Yes Moderate markdown-it 75KB Fast Plugin Very remark Varies Fast Plugin Extremely My pick : marked for simple use, remark for AST manipulation. Markdown Flavors Matter CommonMark — The strict specification GFM — Adds tables, strikethrough, task lists MDX — Markdown + React components Security: Always Sanitize Raw Markdown can contain XSS: <img src= "x" onerror= "alert('XSS')" > Always sanitize the HTML output: import DOMP