Will minified CSS behave the same?

Yes — minification removes bytes the browser ignores (comments, whitespace, redundant syntax) without changing the computed styles. The browser profile is fixed and documented.

No. Processing happens in your browser; the stylesheet never crosses the network.

Why use a fixed browser profile?

It makes output reproducible: the same input always produces the same minified CSS targeting the same browser set, instead of results that shift with trends.

Should I minify CSS in my build pipeline instead?

For sites built with bundlers, yes — but for quick optimizations, legacy assets, or files you receive from others, this tool does the same job privately without a toolchain.

Minify CSS — locally

Shrink stylesheets with standards-based CSS minification, processed entirely in your browser. The browser-support profile is fixed at build time and documented — no surprises.

Open the CSS compressor tool Runs entirely in your browser — files never leave your device.

What this tool does

CSS minification removes comments, whitespace and redundant syntax to produce a smaller stylesheet with identical behavior. This tool uses a maintained CSS minifier (Lightning CSS) with a documented target-browser profile, so the output is predictable rather than experimental.

Gzip the result for delivery, and compare real measured sizes before and after — reported honestly, including when the gain is negligible.

How to minify a CSS file without uploading it

Add the stylesheet. Drop your .css into the home-page tool.
Minify. The minifier runs locally with a fixed browser profile; optionally gzip the output.
Download. Save the minified CSS and link it as usual.

Supported operations

This list is generated from CompressKit's capability registry — only implemented and tested operations appear here.

Reduce file size

Standards-based CSS minification with a fixed target-browser profile, plus optional gzip.

Frequently asked questions

Will minified CSS behave the same?: Yes — minification removes bytes the browser ignores (comments, whitespace, redundant syntax) without changing the computed styles. The browser profile is fixed and documented.
Is my CSS uploaded?: No. Processing happens in your browser; the stylesheet never crosses the network.
Why use a fixed browser profile?: It makes output reproducible: the same input always produces the same minified CSS targeting the same browser set, instead of results that shift with trends.
Should I minify CSS in my build pipeline instead?: For sites built with bundlers, yes — but for quick optimizations, legacy assets, or files you receive from others, this tool does the same job privately without a toolchain.

Ready to try it?

The CSS compressor tool runs on this site with no upload step — your file is processed by your own browser and saved back to your device.

Open the CSS compressor tool