Does this send my code anywhere?

No. Minification runs entirely in your browser using Terser.

Is the output safe to ship to production?

Yes. Terser is the minifier used by webpack, Vite, and most modern JS build tools by default.

Does it support TypeScript?

No. Terser parses standard JavaScript, not TypeScript syntax. TypeScript needs to be compiled to plain JavaScript first, the same way it would before any other Terser-based build step.

Why do variable names become single letters?

Mangle is enabled, which renames local variables and function parameters to the shortest safe name it can find, as long as doing so provably doesn't change behavior.

JavaScript Minifier - Minify JS Online

Overview

Introduction

Every unnecessary byte in a shipped JavaScript bundle costs load time, especially on slower connections.

This tool minifies JavaScript using Terser, the same minifier most modern bundlers run by default, entirely in your browser.

What Is JavaScript Minifier?

A minifier that removes whitespace and comments, shortens variable and function names where safe, and applies basic compression transforms.

The output is functionally equivalent to the input; only its size and readability change.

How JavaScript Minifier Works

Terser parses the code into an AST, applies compression and mangling passes, and re-prints the smallest equivalent code.

A syntax error in the input is reported with its line and column instead of producing output.

When To Use JavaScript Minifier

Use it before shipping a standalone script that isn't already going through a bundler's minification step.

It's also useful for quickly estimating how much a piece of code could shrink.

Often used alongside JavaScript Formatter, JavaScript Validator and JavaScript Obfuscator.

Features

Advantages

Runs entirely client-side.
Uses Terser, the production-grade minifier trusted by major JS build tools.
Reports exact byte savings, useful for judging whether minifying a small script is even worth it.

Limitations

Aggressive mangling can occasionally change behavior in code that relies on `Function.prototype.name` or similar introspection; review minified output before shipping unusual code.

Examples

Verbose function

Input

function add(firstNumber, secondNumber) {
  return firstNumber + secondNumber;
}

Output

function add(t,n){return t+n}

Whitespace is removed and parameter names are shortened to single letters.

Best Practices & Notes

Best Practices

Always keep an unminified source copy; minified output isn't meant to be hand-edited.
Check the size savings panel to confirm the minification was worthwhile for small scripts.

Developer Notes

Uses Terser's `minify()` with `compress` and `mangle` enabled, dynamically imported so the minifier itself doesn't bloat every other tool's bundle.

JavaScript Minifier Use Cases

Shrinking a standalone script before embedding it in a page
Comparing minified vs. unminified size for a code snippet

Common Mistakes

Editing the minified output directly instead of the original source, making future changes much harder.
Debugging a production error directly against mangled output; no source map is generated here, so pairing minification with your build tool's source maps keeps stack traces readable.

Tips

If minification fails, the error points at a syntax problem; run it through the JavaScript Validator first if you're unsure.
Test minified output in the environments you target before shipping, since mangling and compression can occasionally interact with edge-case syntax.

JavaScript Minifier