Developer tools

CSS Minifier

CSS Minifier

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About this tool

About this tool

CSS Minifier compresses stylesheets by stripping comments, whitespace, and redundant separators while keeping selector functionality intact inside your browser. Minified CSS can be copied or downloaded for deployment.

Compress CSS while preserving declarations and selectors. Use the full-width workspace to minify content while reviewing syntax, encodings, protocol fields, and implementation details. The tool accepts plain text, provides focused options, and creates plain text output that you can inspect, copy, download, or save as a local draft.

Built for daily work

How to use this tool

How to use this tool

1

Add the source content

Paste code or technical input, upload a supported plain text file, or load the working example. Check headers, delimiters, syntax, or line structure before processing.

2

Configure the operation

Review the available processing controls. The selected controls determine how the CSS Minifier interprets the source and builds the result.

3

Run the tool

Start the CSS Minifier and review the result, visual preview, and technical report. Correct any reported issue and run the tool again when necessary.

4

Export or continue the workflow

Copy or download the plain text result, save a browser-local draft, or open a related tool for the next conversion, validation, or cleanup step.

Key features

Key features

Strips whitespace, newlines, and comments

Rule spacing, property indentation, and block comments are removed to produce the smallest valid stylesheet.

Last semicolons and trailing zeros

Optional trailing semicolons and unnecessary trailing zeros in numeric values are removed where safe.

Preserves CSS semantics

Selectors, properties, and values remain in their original order. No rules are merged, reordered, or deduplicated.

No autoprefixing or property optimization

The minifier removes only whitespace and comments. It does not optimize shorthand properties or add vendor prefixes.

Practical use cases

Practical use cases

    Private by default

    For local tools, input is processed in your browser and is not sent to application analytics.

    Data processing notice

    Technical details

    Technical details

    Input formatsplain text
    Output formatsplain text
    ProcessingLocal browser processing
    Task controlsthe available processing controls
    Maximum local file25 MB per supported file
    Workspace featuresFocus mode, examples, copy, download, local drafts, and result reports

    Limitations and important notes

    Limitations and important notes

    • Keep an unminified source copy for maintenance and debugging.
    • Large or deeply structured input depends on available browser memory and may process more slowly on mobile devices.
    • The tool implements practical browser-based processing and may not reproduce every feature of specialist desktop software or every vendor-specific extension.
    • Keep the original source and review generated output before production, security-sensitive, financial, legal, or safety-critical use.

    Frequently asked questions

    Frequently asked questions

    Related guides and solutions

    Related guides and solutions

    Browse all guides

    Shrink CSS and JavaScript to speed up your pages

    Every kilobyte of CSS and JavaScript delays your page. Minification removes whitespace, comments, and formatting without changing behavior. The [CSS minifier](tool:css-minifier) and [JavaScript minifier](tool:javascript-minifier) work locally, and the [page speed guide](guide:reduce-image-size-for-website) covers the image side of the same problem.

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    A safe workflow for cleaning text and line-based data

    A step-by-step text cleanup process that uses small reversible changes, diff review, and Unicode awareness instead of destructive one-click normalization.

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    How to reduce image size for a website without visible quality loss

    A practical guide to reducing image size for the web with the [image compressor](tool:image-compressor): why image weight matters, format selection, compression levels, resizing, and verification before publishing.

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