JavaScript Formatter

What does this JavaScript Formatter do?

This free online JavaScript formatter — also called a JS beautifier or JS pretty printer — takes minified, compressed or poorly formatted JavaScript and rewrites it with consistent indentation, spacing and line breaks so it is readable and editable. Paste the output of a bundler, a copy-pasted snippet from a minified library, or a wall of one-line code from a legacy script, and you get clean JS you can actually work with.

The same tool works in reverse. Switch to JavaScript minifier mode and it collapses your code into a compact single-line form, stripping comments and unnecessary whitespace. That is exactly what you want for production: smaller files, faster downloads, and a better PageSpeed score.

Everything runs locally in your browser. The code you paste never leaves your device, there is no signup, and there are no usage limits. Format or minify as much JavaScript as you want, as many times as you want, for personal or commercial projects.

How to format and beautify JavaScript code

1. Paste your JavaScript into the input box on the left. Any JS works — hand-written, minified by a build tool, or copied from a library.
2. Choose your options. Pick the indentation size (2 spaces, 4 spaces or tab) and whether to keep or strip comments.
3. Click Beautify JavaScript. The formatter rewrites your JS with consistent indentation and line breaks. The output appears instantly on the right.
4. Or click Minify JavaScript for production. The output collapses into the smallest possible form, and the stats panel shows how many bytes you saved.
5. Copy or download the result using the buttons above the output. Copy Output puts it on your clipboard; Download .js saves it as a file.

Why use this JavaScript Formatter?

What exactly gets changed?

Here is a complete list of what the formatter and minifier handle, so you know exactly what to expect from each mode.

Note that the minifier does not perform advanced compression like variable renaming, dead-code elimination, or constant folding. For that, use a dedicated tool like Terser or esbuild. This tool focuses on safe, whitespace-level minification that you can trust.

Who uses a JavaScript formatter?

Anyone who reads, debugs, reviews or ships JavaScript benefits from formatting. Here are the most common use cases:

Front-end and full-stack developers

• Format minified JavaScript from a production bundle to debug a runtime error
• Beautify code from a third-party library to understand what it does
• Standardise indentation across a legacy script before a refactor
• Minify JavaScript before shipping to production to reduce file size
• Format pasted snippets from Stack Overflow before pasting into a project

Code reviewers and QA engineers

• Format a diff-friendly version of a minified file for code review
• Inspect what a minified build actually contains (comments, dead code, etc.)
• Prepare a "before / after" size comparison for a performance report

SEO and performance engineers

• Minify JavaScript to improve Core Web Vitals and PageSpeed scores
• Compare input and output byte counts to report compression savings
• Trim render-blocking JS on the critical path

Students and learners

• Format minified code from a tutorial to understand the structure
• See how indentation and spacing affect readability
• Practice writing clean JS with consistent formatting

JavaScript beautify vs. JavaScript minify — what is the difference?

These two operations are opposites, and this tool does both.

If you have readable JS and need to shrink it for production — reducing file size and page load time — use the JavaScript Minifier mode. If you have minified JS and need to understand it, use Beautify JavaScript.

JavaScript formatting best practices

Whatever style you choose, keep it consistent. Here are the conventions most teams follow:

• Use a consistent indent size. 2 spaces is the most common in modern JS; 4 spaces appears in older codebases and some teams still prefer it.
• Always use semicolons (or never use them) — don't mix. Semicolons prevent subtle ASI bugs and make minified output safer.
• Use const by default, let when you need to reassign. Avoid var in new code.
• Prefer arrow functions for short callbacks. Use named function declarations when you need hoisting or a stable this.
• Use template literals for string interpolation. Easier to read than string concatenation.
• Keep functions small. If a function spans more than a screen, consider splitting it.
• Use async/await instead of .then() chains. Cleaner flow, easier error handling.
• Prefer early returns. They reduce nesting and make control flow obvious.
• Add meaningful comments. Explain why, not what — the code already says what.
• Use a linter. ESLint with a shared config (Airbnb, Standard, or your team's) catches issues before they ship.

Frequently asked questions