JavaScript Minifier: free online, fast and secure
JavaScript size directly affects how fast pages become interactive. This minifier uses Terser, the same engine used by modern build tools, to remove whitespace and comments, shorten variable names and simplify code.
Paste your code or open a file, and get optimised output with the size saving. Syntax errors are reported clearly.
How to use JavaScript Minifier
- Paste or open JS. Modern ES2020+ syntax is supported.
- Minify. Terser compresses and mangles the code.
- Copy or download. Deploy the .min.js file.
Why use ConvertKaro JavaScript Minifier? Free, fast and secure
There are many JavaScript Minifier websites, but most of them upload your files, add watermarks or ask you to pay. Here is why this one is better.
100% Free
JavaScript Minifier on ConvertKaro costs nothing. There is no trial, no premium plan and no hidden limit, so you can use it as often as you like.
Fast results
Because nothing travels to a server, results appear almost instantly. Large files are limited only by the speed of your own phone or computer.
Secure and private
Nothing is uploaded. Sensitive files like Aadhaar, PAN, salary slips or contracts stay on your own phone or laptop the whole time.
No signup, no watermark
No account, no email and no watermark on your result. Open the page and start.
Works on every device
Designed for mobile first, so it works just as well on your phone as on a desktop computer.
Real Terser engine
Professional-grade compression, not just whitespace removal.
ConvertKaro vs other websites and apps
| ConvertKaro | Typical website or app | |
|---|---|---|
| Price | Free forever, every feature | Free trial, then paid plans |
| Your data | Stay on your device | Uploaded to a server |
| Signup | Not needed | Often required |
| Watermark or ads on result | Never | Common on free plans |
| Speed | Instant, no upload wait | Depends on upload speed |
| Daily limits | None | Usually limited |
Common uses for JavaScript Minifier
- Shopify theme and WordPress scripts
- Landing page and widget scripts
- Bookmarklets
- Embedding small scripts in HTML
- Reducing bundle size quickly
Tips for the best results
- Keep readable source code in version control.
- Test the minified file before deploying.
- Global variable names are kept so other scripts still work.
- Minify CSS too with CSS Minifier.
Good to know
Small utilities like JavaScript Minifier save time every day: no need to open an IDE, install a package or write a script for a quick check. The tool follows the same standards used by browsers and Node.js, so results match what your code will do. Bookmark this page or add it to your home screen to keep it one click away.
| Price | Free, no limits |
|---|---|
| Processing | In your browser, instant |
| Signup | Not required |
| Watermark | None |
| Works on | Android, iPhone, Windows, Mac, Linux |
| Category | Developer tools |
How JavaScript Minifier keeps your code and data private
Everything you enter into JavaScript Minifier stays on your device. The tool works offline once the page has loaded, because all the logic is in the page itself rather than on a server. We never receive, log or store your code and data, so you can use it at work, at school or for personal matters without worrying about privacy.
Using JavaScript Minifier on your phone
On a phone, open this page in Chrome or Safari, tap the main button and pick or paste what you need. Results download straight to your phone, usually into the Downloads folder or Files app. You can also add this page to your home screen for one-tap access next time.
Who uses JavaScript Minifier?
Here are some of the people who find this tool most useful:
- Web developers and programmers
- Students learning coding and web design
- Digital marketers and SEO specialists
- Testers and support engineers debugging data
- Small business owners managing their own websites
Supported input: Plain text, JSON, CSS, JavaScript, HTML, URLs, Base64, tokens and image files where relevant.
Frequently asked questions
Is my code uploaded?
No. Terser runs in your browser.
Does it support ES6+?
Yes, including modules, arrow functions and async/await.
Why do I get a syntax error?
The code has an error; the message tells you what Terser could not parse.
Is JavaScript Minifier really free?
Yes, completely free. You can use it as many times as you want, and every option on the page is included at no cost.
Is it safe to use JavaScript Minifier online?
Yes. Your data are processed inside your own browser and are never uploaded to our servers, so nobody else can see them.
Does JavaScript Minifier work on mobile?
Yes, the tool is built mobile-first. Open this page on your phone, add your data and download the result directly.
Do I need to install anything to use JavaScript Minifier?
No. JavaScript Minifier works in your web browser. There is no app, plug-in or extension to install.
Will ConvertKaro add a watermark or ask me to sign up?
No. There is no watermark, no login and no email required. Copy or download the result as it is.
Does JavaScript Minifier work offline?
Once this page has finished loading, the tool keeps working even if your internet connection drops, because all processing happens on your device.
Related free tools
People who use this tool often need these too: CSS Minifier, HTML Minifier, JSON Formatter, Regex Tester, Hash Generator.