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JavaScript Minifier

Q: My minified code breaks. What should I check?

Turn on Keep names if your code relies on function.name or class names. Enable Module for files that use import or export. If you target old browsers, set the ECMAScript level to ES5.

Q: Will license comments be kept?

Yes. Comments that start with /*! or contain @license or @preserve are kept by default. Untick Keep /*! comments to remove them too.

Compress your JavaScript with Terser, the minifier behind webpack and Vite. Remove dead code, shorten variable names, drop console calls and ship smaller bundles, without your code ever leaving the browser.

Your code never leaves your device
Powered by Terser
Free HTTP API

Compress Mangle names Keep /*! comments Remove console.*

More options

ECMAScript ES module import / export Top-level mangle globals Keep names functions, classes Extra pass slower, smaller Beautify indent

Ctrl + Enter

Input Paste, type or drop files

Upload

Output Minified code appears here

Original–

Minified–

Saved–

Gzipped–

Time–

Why developers use jsminifier.org

Private by design

Terser runs inside your browser. Your source code is never uploaded, stored or logged.

Industry-grade compression

The same Terser engine used by webpack, Vite and Rollup: dead-code removal, constant folding and name mangling.

Modern JavaScript

Classes, async/await, optional chaining, ES modules and more. Choose the ECMAScript level you ship to.

Clear error messages

Syntax errors show the exact line and column with the offending code, so you can fix them fast.

Combine many files

Drop several scripts at once. They are joined safely in order into a single .min.js file.

Real size stats

Compare original, minified and gzipped sizes, plus a Beautify button to make minified code readable again.

How to minify JavaScript

Add your code. Paste it, type it, or drop one or more .js files onto the input box.
Pick your options. The defaults are safe for production; open the options to fine-tune them.
Minify and ship. Press Minify (or Ctrl + Enter), check how much you saved, then copy or download the .min.js file.

JavaScript Minify API

Automate minification from your build scripts, CI or CMS with a single HTTP request. No key required.

Endpoint: POST https://jsminifier.org/api/
Body: input: your JavaScript (form-urlencoded or multipart)
Optional: format=json for sizes and savings, license=0 to also drop /*! */ comments
Returns: application/javascript with the minified code, or 400 and the error text
Limits: Up to 10 MB per request, 60 requests per minute

The API uses our lightweight server engine (comment and whitespace removal). The browser tool above applies the full Terser optimiser.

curl -X POST https://jsminifier.org/api/ \
  --data-urlencode "[email protected]" \
  -o app.min.js

# sizes and savings as JSON
curl -X POST https://jsminifier.org/api/ \
  --data-urlencode "[email protected]" -d format=json

const res = await fetch("https://jsminifier.org/api/", {
  method: "POST",
  body: new URLSearchParams({ input: code })
});
if (!res.ok) throw new Error(await res.text());
const minified = await res.text();

$ch = curl_init("https://jsminifier.org/api/");
curl_setopt_array($ch, [
  CURLOPT_POST           => true,
  CURLOPT_POSTFIELDS     => http_build_query(["input" => $code]),
  CURLOPT_RETURNTRANSFER => true,
]);
$minified = curl_exec($ch);
curl_close($ch);

import requests

r = requests.post("https://jsminifier.org/api/", data={"input": code})
r.raise_for_status()
minified = r.text

using var http = new HttpClient();
var body = new FormUrlEncodedContent(new Dictionary<string, string> {
    ["input"] = code
});
var res = await http.PostAsync("https://jsminifier.org/api/", body);
res.EnsureSuccessStatusCode();
string minified = await res.Content.ReadAsStringAsync();

Frequently asked questions

What does a JavaScript minifier do?

It rewrites your code into the smallest form that behaves exactly the same. Comments and whitespace are removed, local variable names are shortened (mangling), and unreachable or unused code is dropped. Smaller files download and parse faster.

Which engine does jsminifier.org use?

Terser, the most widely used JavaScript minifier, which also powers the production builds of webpack, Vite and Rollup. It fully supports modern JavaScript, including ES modules, classes and async functions.

Is my JavaScript uploaded to your server?

No. With JavaScript enabled, Terser runs entirely in your browser and your code stays on your device. Only if JavaScript is turned off does the form fall back to our server, which minifies the code in memory and does not keep it.

What does Mangle names do?

It renames local variables and function parameters to short names such as a or b. Global names are left alone unless you enable Top-level, so other scripts on your page keep working.

My minified code breaks. What should I check?

Turn on Keep names if your code relies on function.name or class names. Enable Module for files that use import or export. If you target old browsers, set the ECMAScript level to ES5.

Will license comments be kept?

Yes. Comments that start with /*! or contain @license or @preserve are kept by default. Untick Keep /*! comments to remove them too.

Can I beautify minified JavaScript?

Yes. The Beautify button reformats any JavaScript with clean indentation. Mangled variable names cannot be restored, but the structure becomes easy to read.

Minifying stylesheets too? Use our sister tool cssminify.org to merge rules, shorten values and compress CSS, with the same privacy and API.