What JavaScript syntax errors can it detect?

The validator checks for missing brackets, unclosed parentheses, unterminated strings, missing semicolons, and malformed statements. It attempts to parse the code and reports the line and position of any detected issue.

What file types can I format?

This tool formats JavaScript (.js), JSX (.jsx), TypeScript (.ts), and TSX (.tsx) files. For CSS, use our CSS Formatter, and for HTML, use our HTML Formatter.

Can I use this in my build pipeline?

This is a browser-based tool for quick formatting. For CI/CD pipelines, install js-beautify via npm and use the CLI. Our tool uses the same engine, so the output is identical.

JS Formatter & Beautifier

Format, beautify, and validate JavaScript code. AI can't reliably format code — use our deterministic engine instead.

The Problem We Solve

AI chatbots mess up JavaScript formatting and hallucinate syntax
Manually formatting minified or messy JS is tedious and error-prone
Online formatters either require signup or have usage limits
Minified production code is impossible to read when debugging
No quick way to validate JS syntax before deployment

Our Solution

Deterministic formatting engine — always produces correct, consistent output
One-click beautify, minify, or remove comments
Real-time syntax validation with error line reporting
Instant copy to clipboard
Code size stats before and after minification
100% private browser processing — your code never leaves your device

Indent:

Input JavaScript

Formatted Output

Original Size (bytes)

Formatted Size (bytes)

Minified Size (bytes)

Compression

About JS Formatter & Beautifier

Our free JavaScript formatter helps developers, code reviewers, and students clean up messy JavaScript code. Unlike AI chatbots that can hallucinate syntax errors or produce inconsistent formatting, this tool uses js-beautify — the industry-standard deterministic formatting engine used by VS Code, Atom, and Sublime Text.

Why This Beats AI

Deterministic output — js-beautify always produces the same output for the same input. AI chatbots format code differently every time and frequently introduce syntax errors.
Zero hallucination — AI often adds, removes, or rewords code logic. Our tool preserves your code exactly, only changing whitespace and indentation.
Syntax validation — Our validator catches missing brackets, unclosed parentheses, and other syntax errors that AI frequently overlooks.
True minification — AI cannot reliably minify JavaScript without breaking it. Our deterministic minifier removes whitespace and comments safely.
100% private — All processing happens in your browser. Your code never touches a server. AI tools send your code to third-party APIs.

Features

Beautify — Format messy JavaScript with proper indentation, line breaks, and spacing
Minify — Remove all whitespace and comments for production deployment
Remove Comments — Strip all comments while preserving code structure
Validate Syntax — Check for syntax errors with line number reporting
Indentation Control — Choose 2 spaces, 4 spaces, 1 space, or tab indentation
Size Statistics — See original, formatted, and minified sizes with compression ratio
ES6+ Support — Handles arrow functions, classes, async/await, destructuring, JSX, and TypeScript
Copy to Clipboard — One-click copy of formatted output
100% Client-Side — Zero upload, zero server, zero API keys. Your code stays in your browser.

Supported File Types

This tool formats JavaScript (.js), JSX (.jsx), TypeScript (.ts), and TSX (.tsx) files. For CSS formatting, use our CSS Formatter. For HTML, use the HTML Formatter.

Frequently Asked Questions

How is this different from AI chatbots?

AI chatbots often make mistakes when formatting code, adding incorrect syntax or hallucinating JavaScript properties and methods. Our tool uses a deterministic JavaScript engine (js-beautify) that always produces correct, predictable output based on established formatting rules. The same engine powers VS Code's built-in formatter.

Is my JavaScript code sent to a server?

No. All processing happens entirely in your browser using the js-beautify library loaded from CDN. Your JavaScript code never leaves your device. You can verify by disconnecting your internet after the page loads — the tool still works perfectly.

What syntax errors can it detect?

The validator checks for missing brackets, unclosed parentheses, unterminated strings, missing semicolons, malformed statements, and invalid syntax. It attempts to parse the code using JavaScript's native parser and reports the line number and approximate position of any detected issue.

How much can minification reduce JS file size?

Typically 30-60% reduction. Our minifier removes all unnecessary whitespace, newlines, and comments. For large JavaScript files with extensive documentation, you can expect significant savings. True production minification (which also renames variables) requires a tool like Terser or UglifyJS.

Does it support modern JavaScript (ES6+)?

Yes. js-beautify supports modern JavaScript syntax including arrow functions, classes, template literals, destructuring, async/await, modules (import/export), optional chaining, nullish coalescing, and JSX. It handles both ES5 and all ES6+ features.

Can I format TypeScript with this tool?

Yes, this tool formats TypeScript (.ts) and TSX (.tsx) files. js-beautify handles TypeScript syntax including type annotations, interfaces, enums, generics, and decorators. However, it does not type-check — for that, use the TypeScript compiler directly.

What is js-beautify?

js-beautify (also known as beautifier.io) is an open-source JavaScript library for formatting code. It is the default formatter in VS Code, Atom, Sublime Text, and many other editors. It supports JavaScript, CSS, HTML, and TypeScript formatting with highly configurable options.