CSS Minifier

Compress pasted CSS snippets or local .css files directly in your browser. Your stylesheet is not uploaded, logged, or sent to an API.

Click to choose a CSS file or drop it here

You can also paste CSS directly into the editor below.

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Conservative CSSO settings

The default run removes comments and whitespace but keeps structural optimizations disabled to avoid risky stylesheet rewrites.

Snippet and file input

Paste partial CSS, full stylesheets, media queries, custom properties, or load a local .css file.

Safe measurement

Analytics use only size and reduction buckets. CSS source, URLs, selectors, comments, and filenames stay out of telemetry.

Frequently Asked Questions

Is my CSS uploaded to Convertr?

No. The minifier runs locally with browser JavaScript. Pasted CSS and selected files are not sent to Convertr servers.

Why disable structural optimization by default?

Some aggressive CSS rewrites can change cascade behavior. The first version keeps compression conservative and focused on safe minification.

What happens when CSS has a syntax error?

The parser error is shown in the warnings panel so you can fix the stylesheet before copying output.

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CSS Minifier

Remove safe formatting and comments from pasted CSS to reduce transfer size.

Input
CSS source text and the available minification options.
Output
Minified CSS plus before-and-after size information.
Real limitations
Minification is not semantic validation, prefixing, or dead-code removal; malformed CSS and unusual hacks can require manual review.
Privacy and data handling
CSS source text and the available minification options is processed in this browser tab. Convertr does not receive or store it; closing or reloading the page clears the working state unless the tool explicitly offers a local download.

How to use this tool

  1. Provide CSS source text and the available minification options in the tool controls.
  2. Choose the settings that affect minified CSS plus before-and-after size information, then run the tool.
  3. Review minified CSS plus before-and-after size information before copying or downloading it.

Common failure modes

Unclosed blocks, invalid strings, or syntax the parser cannot understand is returned as an error instead of altered output.

Useful example

Minify a formatted .card rule by removing indentation, comments, and unnecessary spaces while preserving its declarations.