Minify JavaScript Online — Free JS Minifier

Minify JavaScript code instantly with our free online tool. Compress JS for production, reduce file size, or concatenate multiple files. All processing happens in your browser — no code sent to any server.

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JavaScript Minification

Minify JavaScript online with Terser. Compress JS for production — instant browser processing, no uploads.

Features

Reduce the size of your JavaScript code by removing spaces, comments and unnecessary characters.

Minify

Reduce the size of your JavaScript code by removing spaces, comments and unnecessary characters.

Package used

Terser

v5.47.1

Terser is a modern JavaScript compressor that optimizes the size and performance of your code.

Basic example

Input code

function calculateTotal(items) {
  let total = 0;
  for (let i = 0; i < items.length; i++) {
    total += items[i].price;
  }
  return total;
}

const products = [
  { name: 'Laptop', price: 999 },
  { name: 'Mouse', price: 25 }
];

console.log('Total:', calculateTotal(products));

Minified code

function calculateTotal(e){let t=0;for(let o=0;o<e.length;o++)t+=e[o].price;return t}const products=[{name:"Laptop",price:999},{name:"Mouse",price:25}];console.log("Total:",calculateTotal(products));

JavaScript optimization guide

Minification options

ECMAScript Version

Defines the target ECMAScript version for minification (ES5, ES2015, ES2017, ES2020, ES2022)

Examples by ECMAScript version:

Original code (ES2022)

const data = { name: 'test' };
const { name } = data;
console.log(name);

ES2022

const{name:data}=data;console.log(data)

ES5

var data={name:'test'};var name=data.name;console.log(name)

Compression Level

Controls the aggressiveness of compression (conservative, normal, aggressive)

ConservativeConservative - Minimal compression, safer

NormalNormal - Balance between size and compatibility

AggressiveAggressive - Maximum compression, may break some code

Compression examples:

Original code

function calculateTotal(items) {
    let total = 0;
    for (let i = 0; i < items.length; i++) {
        total += items[i].price;
    }
    return total;
}

Conservative

function calculateTotal(items){let total=0;for(let i=0;i<items.length;i++)total+=items[i].price;return total}

Normal

function calculateTotal(t){let e=0;for(let l=0;l<t.length;l++)e+=t[l].price;return e}

Aggressive

function e(e){let t=0;for(let n=0;n<e.length;n++)t+=e[n].price;return t}

Preserve Class Names

Preserves CSS class names in string literals

Comparison with/without option:

Original code

element.className = 'my-class';
element.setAttribute('class', 'another-class');

With preserveClassNames: true

element.className='my-class';element.setAttribute('class','another-class')

With preserveClassNames: false

element.className='a';element.setAttribute('class','b')

Difference

CSS class names are preserved in strings

Preserve Function Names

Preserves function names for debugging

Comparison with/without option:

Original code

function myFunction() { 
    return true; 
}
const obj = { myMethod() { return false; } };

With preserveFunctionNames: true

function myFunction(){return!0}const obj={myMethod(){return!1}}

With preserveFunctionNames: false

function a(){return!0}const obj={b(){return!1}}

Difference

Function names are preserved for debugging

Remove Console

Removes all console.log, console.warn, etc. calls

Comparison with/without option:

Original code

console.log('Debug info');
console.warn('Warning message');
const result = calculateTotal(items);
console.log('Result:', result);
return result;

With removeConsole: true

const result=calculateTotal(items);return result

With removeConsole: false

console.log('Debug info');console.warn('Warning message');const result=calculateTotal(items);console.log('Result:',result);return result

Difference

All console.* calls are removed

Remove Debugger

Removes debugger statements from code

Comparison with/without option:

Original code

if (condition) {
    debugger;
    return true;
}
function test() {
    debugger;
    return false;
}

With removeDebugger: true

if(condition)return!0;function test(){return!1}

With removeDebugger: false

if(condition){debugger;return!0}function test(){debugger;return!1}

Difference

Debugger statements are removed

See Beautify indentation options →

How to Unminify JavaScript Online

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JavaScript Beautifier vs Unminifier — What's the Difference

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Concatenating JavaScript Files

Combining multiple JavaScript files into one reduces HTTP requests and can improve page load performance. Use our concatenation feature to merge multiple JS files, then optionally minify the result for maximum compression. This is especially useful for projects that don't use a bundler like Webpack or Rollup.

Frequently Asked Questions — Minify

Everything about minification

Why minify JavaScript?

JavaScript minification reduces file sizes by removing whitespace, comments and shortening variable names. Typical size reductions range from 30% to 70%.

How does JavaScript minification work?

Our tool uses Terser, the industry-standard JavaScript compressor. It removes unnecessary characters while optionally mangling variable names. The minified code is functionally identical to the original.