JavaScript Formatter - Beautify & Prettify JS Online

Beautify JavaScript in Your Browser

This JavaScript formatter turns minified, obfuscated, or inconsistently styled JS into clean, properly indented code you can actually read. Paste a snippet on the left and the beautified result appears on the right the moment you stop typing — no button to press, nothing sent to a server.

Built on Prettier with the Babel parser — the same opinionated formatter used across millions of projects — so the output matches the style teams already trust in their editors.

When to Use It

Unminify a Bundle

Expand a one-line or minified script back into readable, line-broken code so you can inspect and debug it.

Standardize Style

Enforce consistent quotes, semicolons, and trailing commas across snippets copied from different sources.

Review Pasted Code

Make tutorial samples, Stack Overflow answers, or AI-generated snippets readable before you study or commit them.

How to Format JavaScript Code

Add Your Code

Type or paste JavaScript into the Input panel. You can also Upload a .js file (read locally, never sent anywhere) or click Sample to load an example.

Watch It Format

The beautified, syntax-highlighted output appears automatically after a short pause in typing. Press Ctrl + Shift + F to reformat on demand.

Tune the Options

Choose an indent (2, 3, 4, 8 spaces or Tab), set the print width, and toggle semicolons, quotes, and trailing commas. The output re-formats immediately.

Copy or Download

Click Copy to send the result to your clipboard or Download to save a .js file. Use the Edit toggle to tweak the output by hand first.

Private by design. Formatting runs entirely in your browser via Prettier — nothing is uploaded, so it is safe for proprietary or unreleased source.

Formatting Options & Features

JavaScript Style Controls

Prettier is opinionated by design, but these controls let you match your project's style guide. Every change re-formats the output instantly.

Option	Choices	What It Controls
Indent	2 · 3 · 4 · 8 spaces · Tab	Indentation width and character used per nesting level (default 4 spaces).
Print Width	80 · 100 · 120	Line length Prettier targets before wrapping long statements (default 80).
Semicolons	Yes · No	Whether statements end with a semicolon (default Yes).
Quotes	Double · Single	Quote style used for string literals (default Double).
Trailing Comma	All · ES5 · None	Commas after the last item in multi-line arrays, objects, and parameter lists (default All).

Built-In Tools

Auto-Format on Input

Output refreshes shortly after you stop typing, with Prism syntax highlighting and line numbers on both panels.

Upload & Download

Load a local .js file or export the formatted result as formatted.js with one click.

Editable Output

Switch the result panel to a CodeMirror edit mode to make manual tweaks before copying or downloading.

Syntax Error Detection

If your code cannot be parsed, the formatter shows a clear error message instead of producing broken output — so you know exactly what to fix. A status bar reports Ready, Formatted, or Error along with the line count and file size.

New here? Click Sample to load a deliberately messy snippet and watch it beautify instantly.

Frequently Asked Questions

Is my JavaScript code sent to a server?

No. All formatting happens locally in your browser. Uploaded files are read with the browser's FileReader and never leave your device, which makes the tool safe for proprietary and confidential source.

What is the difference between formatting and minifying?

Formatting (beautifying) adds indentation, line breaks, and consistent spacing to make code readable. Minifying does the opposite — it strips whitespace to shrink file size. This tool beautifies; use a minifier when you want to compress code for production.

Does it support modern ES6+ and JSX syntax?

Yes. The Babel parser handles modern JavaScript — arrow functions, async/await, destructuring, template literals, optional chaining, and JSX — so contemporary code is formatted correctly.

Can I customize the indentation and style?

Yes. Pick 2, 3, 4, or 8 spaces (or Tab) for indentation and set the print width, then toggle semicolons, quote style, and trailing commas from the toolbar. The output re-formats as soon as you change any option.

Will formatting change how my code runs?

No. Prettier only rewrites whitespace and cosmetic style — indentation, quotes, semicolons, and line breaks. The behavior of your JavaScript stays exactly the same.

What happens if my code has a syntax error?

Prettier cannot format code it cannot parse, so the tool shows an error message describing the problem instead of guessing. Fix the reported issue and the formatted output appears as soon as the code is valid.

Is there a size limit on the code I can format?

There is no fixed limit. Because formatting runs in your browser, speed depends on your device — large files still format in moments on a modern machine, and the status bar shows the line count and file size.