JavaScript Beautifier & Minifier

A JavaScript beautifier reformats code with consistent indentation and line breaks, which makes minified scripts readable when you're debugging a production issue or studying how a page works. A minifier does the reverse for your own code, producing the smallest equivalent script so pages load faster.

This tool does both in the browser: js-beautify for formatting with your choice of indentation, and Terser, the minifier behind most JavaScript bundlers, for production-grade minification with compression and variable mangling. The size before and after is shown so you can see what you saved.

Minifying uses Terser with compression and name mangling: it removes whitespace and comments, shortens local variable names, and rewrites code into shorter equivalents, such as an if statement into &&. Top-level names stay, because other scripts may use them. Syntax errors are reported instead of producing broken output.

Terser is a large library, so it's downloaded only when you press Minify. Beautifying uses js-beautify, which restores indentation but can't restore the original variable names once they've been mangled.