⚡ JS Minifier
Shrink JavaScript files with a basic minifier for smaller files. Useful for quicker page loads and smaller payloads. Free, unlimited, private — works entirely in your browser.
How to use
- Paste your JavaScript code into the input box, or upload a .js file from your computer.
- Choose your options: strip comments, remove extra whitespace, and optionally keep or remove line breaks.
- Click the Minify button to compress your code instantly in the browser.
- Copy the minified output or download it as a .min.js file, ready for production.
FAQ
Is it really free?
Yes — every tool on this site is 100% free with no limits, no signup and no watermarks.
Is my data private?
Absolutely. All processing happens locally in your browser. Your files are never uploaded to any server.
📖 Step-by-step tutorial: New to this tool? Read our complete guide to minifying JavaScript online — with practical examples.
What exactly does minification remove?
Minification strips comments, unnecessary whitespace, and line breaks that humans need but browsers don't. This basic minifier does not rename variables or restructure code — for aggressive optimization with variable mangling, use a build tool like Terser or esbuild.
How much smaller will my file get?
Typical savings are 20–40% depending on how heavily commented and formatted the original is. A well-commented 100 KB file often drops to 60–70 KB. For maximum savings, combine minification with gzip/Brotli compression on your server, which shrinks text files another 60–70%.
Is it safe to minify any JavaScript?
This minifier is conservative — it only removes whitespace and comments without changing code semantics, so it's safe for standard scripts. However, always test the minified file: code relying on specific formatting (rare, but possible with some regex or eval tricks) could behave differently. Keep your original source file as the master copy.
Should I minify during development?
No — develop with readable, commented source files and minify only for production deployment. Debugging minified code is painful. Better yet, use source maps with a proper build pipeline; this online tool is ideal for quick one-off minification of small scripts.
JS Minifier — Complete Guide
JavaScript files ship with generous whitespace, descriptive comments and readable formatting — all essential for developers, all dead weight for browsers. Minification strips that weight, shrinking files by 20–40% and speeding up every page load. This free tool minifies your JS instantly in the browser, with zero uploads and zero setup.
How it works
The minifier parses your code and removes everything the JavaScript engine doesn't need: single-line and multi-line comments, indentation, line breaks, and spaces around operators and punctuation. String contents and regex literals are carefully preserved — only structurally unnecessary characters are removed. Because it's a straightforward whitespace/comment stripper (not a full AST optimizer), the output remains semantically identical to the input.
What this minifier does vs. build tools
- This tool: removes comments + whitespace. Fast, safe, predictable. Perfect for small scripts, snippets and quick jobs.
- Terser / UglifyJS: also shortens variable names, drops dead code, and simplifies expressions. 10–20% smaller output, but needs a build setup.
- esbuild / swc: full bundlers that minify as part of a build pipeline. Best for real projects with modules and dependencies.
Rule of thumb: use this online tool for one-off files under a few hundred KB; graduate to a build tool when your project grows.
Best practices
Never edit minified files — treat them as build artifacts. Keep the original app.js as your source of truth and generate app.min.js for deployment. Always test the minified version in a browser before shipping; while this minifier is conservative, testing catches surprises. Enable gzip or Brotli on your server — minification plus compression compounds dramatically (a 100 KB file can become ~20 KB over the wire). Use the .min.js convention so it's obvious which files are production builds.
When minification isn't enough
If your scripts are still heavy after minifying, the code itself is the issue, not the formatting. Consider code splitting (load only what's needed per page), tree shaking unused library code, or replacing heavy dependencies with lighter alternatives. Minification is the final polish — architecture is the real diet.