What does minifying CSS do?
Minification removes comments, extra whitespace, and unnecessary semicolons or line breaks from a stylesheet without changing what it renders. Smaller CSS files download and parse faster — a meaningful win on a render-blocking resource loaded on every page.
Should I keep an unminified copy?
Yes — minified CSS is hard to read or debug. Keep your source stylesheet as-is for editing, and minify only the version you ship to production (ideally as part of your build process, with this tool useful for quick one-off checks).
Frequently asked questions
Does minifying change how my CSS behaves?
No — it only removes whitespace, comments, and redundant characters that don't affect rendering. The selectors, properties, and values are preserved exactly.
Should I minify by hand or use a build tool?
For production, a build-time minifier (esbuild, cssnano, a bundler plugin) is more thorough and safer for edge cases like complex selectors or vendor-specific hacks. This tool is best for quick, one-off minification.
Is my CSS uploaded when I use this tool?
No. Minification happens instantly in your browser — nothing is sent to a server.