CSS minifier
Paste or drop a stylesheet and get a smaller one back, live.
How it works
- 01Paste your CSS or drop a .css file into the box.
- 02Choose whether CSSO may merge and restructure rules, and whether to keep /*! license comments.
- 03Check the size you saved, then copy the result or download it as a .min.css file.
Questions
›Is it safe to restructure CSS?
Restructuring lets CSSO merge rules that share selectors or declarations and move them where the cascade allows. It is designed to render exactly the same and usually saves the most. If you would rather keep your rules in their original order and shape, turn it off.
›What about CSS nesting and other new syntax?
CSSO doesn't understand some newer syntax yet, such as native CSS nesting and media range queries like (width >= 600px). Instead of quietly dropping those rules, the tool switches to a safe mode that only removes comments and whitespace, and tells you which line it couldn't parse.
›Can I minify Sass or Less?
Not directly. This tool minifies plain CSS, so compile Sass, SCSS or Less to CSS first and minify the result here.
›What does the gzipped size mean?
Most web servers compress CSS with gzip or Brotli before sending it, so the gzipped size is closer to what visitors actually download. It is measured with your browser's built-in gzip.
›Is my data uploaded anywhere?
No. This tool runs entirely in your browser, and Rounder never sends what you type or drop in to a server, ours or anyone else's. Once the page has loaded, along with any AI model the tool uses, it even works offline.