FileopiaHTML, CSS & JavaScript Minifier
Minify HTML, CSS and JavaScript online to reduce file size and speed up websites. JavaScript is compressed with Terser. Free, private and runs in your browser.
- Upload
- Options
- Download
- ✓ 100% free
- ✓ No sign-up
- ✓ No limits
- 🔒 Files never leave your device
How to: HTML, CSS & JS Minifier
- Paste HTML, CSS or JavaScript.
- The language is detected automatically, or choose it.
- Copy the minified code or download the file.
Every byte a visitor downloads slows your site a little, especially on mobile networks. Minifying removes comments, whitespace and unnecessary characters from HTML, CSS and JavaScript, often cutting file size by 20–60%. This tool uses Terser, the same JavaScript minifier used by popular build tools, plus fast CSS and HTML minifiers, all running in your browser.
Common uses
- Shrink CSS and JavaScript for small sites without a build pipeline.
- Minify HTML email templates and landing pages.
- Prepare compact code snippets for widgets, bookmarklets and embeds.
- Check how much smaller your files could be before setting up a bundler.
Tips for best results
- Keep the original, readable source – minified code is hard to edit.
- Turn off mangling if other scripts call your global variable names.
- Combine minification with gzip or Brotli on your server for the best results.
- Use the JSON formatter's minify mode for JSON files.
What each minifier does
The CSS minifier removes comments and whitespace, drops the last semicolon in each block and shortens colours such as #ffffff to #fff. The HTML minifier collapses whitespace between tags and removes comments, while leaving pre, textarea, script and style blocks untouched unless you choose to minify inline code. JavaScript is parsed into a syntax tree by Terser, compressed and printed without comments.
Minification and Core Web Vitals
Smaller files load and parse faster, which helps Largest Contentful Paint and Interaction to Next Paint, two of Google's Core Web Vitals. For large sites, a build tool such as Vite or esbuild is the best long-term option; for small sites, landing pages and quick fixes, this minifier gets you most of the benefit in seconds.
Why use Fileopia for HTML, CSS & JS Minifier?
| Fileopia | Typical upload-based sites | |
|---|---|---|
| What you type is sent to a server | No – stays in your browser | Often |
| Sign-up required | Never | Often for bigger jobs |
| Hourly / daily task limits | None | Common on free plans |
| Works offline after loading | Yes, for most tools | No |
Private by design
Everything you type is calculated by JavaScript in this tab. Nothing is sent to Fileopia or anyone else, and there are no accounts or tracking cookies tied to what you enter.
- Test it yourself: once this page has loaded, switch off Wi‑Fi or mobile data and run the tool – it keeps working.
- Check the network: open your browser’s developer tools (F12 → Network) while processing; you will see no file upload requests.
- Nothing to delete: close the tab and the data is gone – there is no server copy, no retention period and no account.
Frequently asked questions
Will minifying break my code
Minification removes whitespace and comments and shortens local variable names without changing behaviour. Test the result, especially for HTML with whitespace-sensitive inline elements.
Which JavaScript features are supported
Modern ES2023 syntax, including modules, classes, async/await and optional chaining, via the Terser engine.
Is HTML, CSS & JS Minifier really free?
Yes. Every tool on Fileopia is 100% free with no file limits, no sign-up and no watermarks. The site is supported by unobtrusive ads.
Are my files uploaded to a server?
No. Fileopia processes your files directly in your browser using JavaScript. Your documents never leave your device, so they stay completely private.
Does it work on mobile?
Yes. Fileopia works in any modern browser on Android, iPhone, iPad, Windows, Mac and Linux.