Free HTML/CSS/JS Minifier Online
Free HTML/CSS/JS Minifier Online is a free online tool by US AI. Remove whitespace & comments. It runs completely in your browser — no signup, no download, works on mobile and desktop. Our JavaScript minifier typically shrinks JS bundles by 20–40%, speeding up page loads and boosting PageSpeed and Core Web Vitals scores.
📖 How to use
- Paste your HTML, CSS or JS and press Minify to strip whitespace and comments, then copy the smaller code.
- Open the tool with the button above — it loads instantly.
- Your work stays on your device; nothing is uploaded anywhere.
✨ Why use this tool?
US AI's free html/css/js minifier online is fast, private and 100% free forever. Bookmark this page and share it with anyone who needs it.
✂️ What gets removed
When you minify CSS, the tool safely strips out everything a browser doesn't need:
- Whitespace and line breaks between rules and declarations
- Comments — except
/*! license */comments, which are preserved - Unnecessary last semicolons before a closing brace
- Redundant units:
0pxbecomes0 - Shortened colors:
#ffffffbecomes#fff
❓ Frequently asked questions
What does a code minifier do?
It strips whitespace, line breaks, and comments from HTML, CSS, and JavaScript, producing a smaller file that loads faster in the browser.
Will minifying break my code?
No. Minification only removes unnecessary characters — your code runs exactly the same, just in a smaller package.
How much smaller do files get after minifying?
Unminified files typically shrink by 20–40%, which speeds up page loads and can improve your site's performance scores.
Will minifying break calc() or @media queries?
No. Required spaces around + and − inside calc() are preserved, and @media rules minify safely — your responsive layouts keep working exactly as before.
What's the difference between minifying and gzipping CSS?
Minifying permanently removes unnecessary characters from your stylesheet, while gzip compresses the file during transfer. Best practice is to do both — minify first, then let your server gzip the smaller file.
Can I keep license/copyright comments while minifying?
Yes. Comments that start with /*! are preserved by convention, so your license and attribution headers stay intact in the minified output.
Does the minifier support modern JavaScript (ES6+)?
Yes. The minifier safely handles modern JavaScript including ES6+ syntax like arrow functions, template literals, classes and modules — your code is compressed without changing how it runs.
Should I keep my original file after minifying?
Yes. Always keep your original, readable file for editing, and deploy only the minified copy — minified code is hard to read and debug, so make edits in the original file and minify it again.
How does minifying JavaScript help SEO and PageSpeed scores?
Smaller JavaScript files download and parse faster, which improves load times and Core Web Vitals like LCP — factors Google uses in ranking. Minifying is one of the quickest free wins for page speed.