DEVELOPER TOOL
CSS Minifier & Compressor
Shrink CSS for production using CSSO, entirely in your browser.
About this tool
Paste CSS to shrink it for production — stripping whitespace and comments, shortening color values and zero units, merging duplicate rules, and other safe structural optimizations. This uses CSSO, a CSS minifier that also restructures the stylesheet for better compression, running entirely in your browser.
Nothing is uploaded — your stylesheet is minified locally and never leaves your device.
Frequently asked questions
- Is this safe to use on production stylesheets?
- CSSO is a mature, widely used CSS minifier that focuses on safe, structure-preserving optimizations. As with any build step, it's still good practice to visually check your site after minifying, especially with complex or unusual CSS.
- Does it remove unused CSS classes?
- No — this only minifies and restructures the CSS you provide; it doesn't know which classes your HTML actually uses, so nothing is removed based on usage. Dead-code removal for CSS requires analyzing your HTML/JS alongside the stylesheet, which is outside what a pure minifier does.
- What happens with invalid CSS?
- CSS parsers are generally lenient and try to recover from small errors rather than fail outright, so malformed input may produce unexpected or empty output rather than a clear error message — double-check the source if the result looks off.