Beautify and format JavaScript code. Unminify and indent JS for readability.
This free online JavaScript beautifier and unminifier uses the battle-tested js-beautify library to transform compressed, obfuscated, or poorly formatted JS code into clean, properly indented source code. It is indispensable for developers who need to inspect third-party scripts, debug minified bundles, or understand how an unfamiliar library works. All formatting runs entirely in your browser - no code is ever sent to a server.
The JS Beautifier uses the js_beautify function from the widely-used js-beautify library - the same engine that powers the Beautify extension in VS Code and Atom. It tokenizes your JavaScript, reconstructs it with 2-space indentation, consistent brace placement, and proper spacing around operators, and handles modern syntax including arrow functions, template literals, destructuring, and async/await. The library runs entirely in your browser, so no code is ever transmitted to a server.
Yes - the beautifier is excellent for unminifying JavaScript. It restores indentation and line breaks to minified bundles, making them readable for debugging or security auditing. However, it does not reverse true obfuscation techniques like variable name mangling (e.g., a, b replacing meaningful names), string encoding, or control-flow obfuscation. For those cases, a dedicated deobfuscator is needed after beautifying the syntax structure.
Yes - all processing is client-side. The js-beautify library is loaded once from CDN and then runs locally within your browser tab. Your code is never sent over the network after that initial library load, so proprietary algorithms, API keys embedded in scripts, or sensitive business logic are never exposed to any external server or third party.
No - JavaScript's execution is not affected by whitespace or indentation. The beautified output is semantically identical to the original: the same functions, closures, variables, and execution order are preserved. The only exception would be code that relies on automatic semicolon insertion (ASI) edge cases with specific line-break placement, which is rare in well-written code and is handled correctly by js-beautify.
Prettier is an opinionated formatter designed for development workflows - it integrates with editors and enforces a strict, unchangeable style. js-beautify is less opinionated and more permissive, making it better for one-off formatting tasks where you just need readable code fast. This online tool requires no installation, no config files, and no Node.js - it works instantly in any browser, making it ideal for quick inspections rather than ongoing project-wide style enforcement.