Minify CSS in your browser with exact byte measurements. Level 2 merging is opt-in and clearly labelled because it can reorder declarations.
Paste CSS, choose the level, then minify.
The minified CSS appears here, with exact byte savings.
Limit for uploaded files: 2 MB. Pasted text is not truncated by the tool — your browser’s memory is the ceiling.
Your file is never sent to a server. It is read and processed by your own browser, and the results are not stored.
Level 1 is safe: it removes bytes and keeps the meaning. Level 2 reorders declarations and merges rules, which is legal CSS but can outrank or undercut your specificity in subtle cases. When in doubt, ship level 1 — the difference is usually a handful of bytes.
Custom properties are not glued to their definitions, so minifying a stylesheet with extensive theming at level 1 is the conservative choice.
The before/after figures are exact encoded bytes, not characters, so the percentage respects multibyte content in comments or strings.
No. CSS Minifier runs in your browser, and the file is read there rather than sent to a server for processing. Our host still sees ordinary page-request metadata, which is described on the privacy page.
Yes, CSS Minifier is free, with no paid tier, no account, and no watermark added to your output. The limits are technical rather than commercial: file size, page count and supported formats are listed on this page.
CSS Minifier supports .css, .txt files up to 2MB directly in your browser.
Level 1 removes whitespace, zero units and duplicates while preserving declaration order and selector structure. Level 2 additionally merges selectors and reorders declarations, which can change which rule wins in edge cases. Level 2 is never on by default.
No. clean-css preserves calc() expressions and custom property definitions and values. It may reduce zero units and convert colours, which is what you asked of a minifier.
It reports errors and warnings from the parser with context. A clean result means the CSS tokenised successfully; it does not guarantee your browser paints what you expect.
No. Everything runs in this tab; the file stays on your device.