Free JavaScript Minifier Online
Minify JavaScript code online. Remove comments and whitespace to reduce JS file size. Free JS minifier.
Key Features
Everything you need in one free tool
Completely free with no registration, and no hidden charges.
browser-side workflows is done locally in your browser. Your data stays private.
Instant results using browser-native APIs and optimized algorithms.
Key Takeaways
- This tool runs entirely in your browser, so your JavaScript is processed on your device, and it strips comments, collapses whitespace, and trims spaces around operators and punctuation.
- It uses lightweight regex-based minification, not a real parser, so it does not rename variables or do dead-code removal or tree shaking; use Terser, esbuild, or your bundler for production builds.
- Because it removes anything matching // or /* */ even inside strings, code containing URLs, regex literals, or comment-like text can break, so test such output carefully or use a syntax-aware minifier.
- Since newlines are collapsed into spaces and no semicolons are inserted, add explicit semicolons at statement ends before minifying if your code relies on automatic semicolon insertion.
How to Minify JavaScript Online
Paste your JavaScript
Copy your source code into the Input JavaScript box. The tool runs entirely in your browser, so nothing is uploaded to a server. You can paste a single function or a full script file.
Click Minify JS
Press the Minify JS button. The tool strips single-line and block comments, collapses runs of whitespace, and removes spaces around common operators and punctuation such as braces, semicolons, commas, and parentheses.
Check stats and copy
Review the size readout showing original size, minified size, and bytes saved with a percentage. Use Copy Result to grab the output, or Clear to reset both fields and start over.
What This Minifier Does and Does Not Do
This tool performs lightweight, regex-based minification in your browser. It is fast and good for quick size reduction, but it is not a full JavaScript parser. The table below shows which transformations are applied so you can set expectations before pasting production code.
| Transformation | Applied | Notes |
|---|---|---|
| Remove line comments (//) | Yes | Matched by pattern, including any that appear inside string literals. |
| Remove block comments (/* */) | Yes | Removed everywhere, including inside strings or regex literals. |
| Collapse whitespace and newlines | Yes | Multiple spaces, tabs, and line breaks become a single space. |
| Trim spaces around operators | Yes | Applies to braces, semicolons, commas, and arithmetic or logical operators. |
| Rename or shorten variables | No | Identifier names are left unchanged. |
| Dead code removal or tree shaking | No | Use a bundler such as Terser or esbuild for those optimizations. |
When to Use This Tool
Quick size checks
Great for pasting a snippet and instantly seeing how many bytes comments and whitespace add. The stats line gives you original, minified, and percent saved at a glance.
Inline scripts and demos
Handy for shrinking small inline scripts, code samples, or bookmarklets where running a full build pipeline would be overkill.
Production bundles
For shipping production code, prefer a dedicated minifier like Terser, esbuild, or your bundler. They parse the syntax and rename variables for far smaller, safer output.
Code with tricky strings
If your code contains URLs, regex literals, or comment markers inside strings, test the output carefully. A regex-based pass can alter content it cannot tell apart from real comments.
Common Problems and Fixes
Minified code throws errors
This minifier collapses newlines into spaces and does not add semicolons. If your code relies on automatic semicolon insertion across line breaks, add explicit semicolons at statement ends before minifying.
Part of a string disappeared
The tool removes anything matching // or /* */ even inside string literals. If a string contains a URL like https://example.com or comment-like text, the trailing part may be stripped. Escape or split such strings, or use a syntax-aware minifier instead.
Regular expressions break
Slashes in regex literals can be misread as comment markers, and operator spacing rules can run characters together. Review any code that uses inline regular expressions after minifying.
Copy button does nothing
Copying uses the browser clipboard API, which requires a secure context. Make sure the page is loaded over HTTPS and that the output box is not empty before clicking Copy Result.
About This Tool
Minify JavaScript by removing comments and unnecessary whitespace to reduce file size. This free tool works entirely in your browser for maximum privacy and convenience.
Frequently Asked Questions
Is this tool completely free?
Yes. The tool is 100% free to use with no registration, no subscription and no usage limits.
You can use it as many times as you need for personal or commercial projects without any cost.
We believe developer and productivity tools should be accessible to everyone without paywalls.
Is my data secure?
Yes. Everything runs locally in your browser using JavaScript. No data is transmitted to our servers — your files never leave your device.
You can safely use this tool with sensitive or confidential information without privacy concerns.
We do not log or store any input you provide to this tool.
Does this work on mobile devices?
Yes. The tool is fully responsive and works in any modern mobile browser on iOS and Android.
The interface adapts to smaller screens while maintaining full functionality.
All buttons, inputs and outputs are accessible on touch devices.
What browsers are supported?
The tool works in all modern browsers including Google Chrome, Mozilla Firefox, Apple Safari and Microsoft Edge.
We recommend keeping your browser up to date to ensure the best experience and access to the latest browser APIs.
Internet Explorer is not supported.
Do I need to install any software?
No. The tool runs entirely in your web browser with no downloads, plugins or installations required.
This makes it accessible from any device without modifying your system.
Simply open the page and start using the tool immediately.
How accurate are the results?
The tool uses browser-native APIs and standard algorithms to deliver accurate results consistent with industry expectations.
Where applicable, we implement well-tested open standards such as the Web Crypto API for hash generation and the native JSON parser for JSON tools.
If you encounter any result that seems incorrect, please try clearing and re-entering your input.
Can I use this tool in commercial projects?
Yes. The tool is free for personal and commercial use with no attribution required.
You can use generated outputs such as passwords, UUIDs and text in any project without restrictions.
The tool itself may not be resold or redistributed but using its outputs is completely unrestricted.
Where can I get help if I have a problem?
For questions or issues you can reach us through our contact page.
We monitor feedback and release regular updates to improve accuracy and add features.
Community suggestions are welcome and have shaped many of the options available in our tools.
Sources and References
Format and tool details on this page are based on the official specifications and documentation below.
- ECMAScript Language Specification- ECMA-262
- JavaScript- MDN Web Docs