JavaScript Formatter
Format and beautify JavaScript code online, free.
Input
Output
What Is the JavaScript Formatter?
You've just received a 2,000-character single-line JavaScript blob from a third-party API, or you pulled a minified bundle from production trying to track down a bug — and it's completely unreadable. That's exactly what this tool is for. The JavaScript Formatter adds proper indentation, line breaks, and spacing so the structure becomes obvious in seconds. The ECMAScript specification defines the language, and tools like Prettier and ESLint handle this in CI pipelines — but when you just need a quick format right now, this does it in your browser. No code leaves your machine, so it's safe to use with API keys, tokens, or any production data. webpack and Rollup are the most common bundlers that produce minified output you'd want to format for debugging.
This tool runs entirely in your browser. Nothing is sent to a server. Paste JS or upload a file; get formatted output. Use Minify for production bundles. For validation, use JavaScript Validator. For minifying only, use JavaScript Minifier.
How to Use This Tool
Paste or Upload
Paste JavaScript into the left panel or upload a .js or .txt file. Use Sample to load example code. Use Clear to reset.
Check the Output
The right panel updates automatically with formatted code. Use Minify to produce a compact version for production.
Copy or Download
Use Copy or Download to get the result. For JSX/React, use JSX Formatter. For TypeScript conversion, use JavaScript to TypeScript.
JavaScript Formatting Examples
Here is an example of formatting minified JavaScript code.
Example: Subscriber plan lookup
Minified input:
Formatted output:
When the JavaScript Formatter Helps
When debugging minified code, reviewing bundles from webpack or rollup, or learning from production scripts, formatting makes the structure visible. Great for stack traces, third-party code, and quick readability checks. AI coding assistants like Google Gemini or Grok can help explain complex JavaScript—paste the formatted version for clearer analysis. The ECMAScript spec defines the language. For obfuscated code, use JavaScript Deobfuscator first.
Frequently Asked Questions
Is my data private?
Yes. Formatting runs entirely in your browser. No data is sent to any server.
Formatter vs Minifier?
Formatter adds indentation for readability. Minifier removes whitespace and comments for smaller file size. This tool can do both.
Does it support ES6+?
Yes. Modern JavaScript syntax (arrow functions, classes, async/await) is supported.
What about JSX?
For JSX and React code, use JSX Formatter.
Can it fix syntax errors?
No. Invalid JavaScript will show an error. Use JavaScript Validator to check syntax first.
Related Tools
Learn more: ECMAScript, MDN JavaScript, webpack, rollup, source maps, Vite, TypeScript.