CSS Minifier - Compress CSS Code Online

Minify your CSS instantly with our free CSS Minifier. This tool removes comments, whitespace, line breaks, and unnecessary separators from your stylesheets to shrink their size and speed up page loads. It is ideal for optimizing websites and web apps for production. Simply paste your CSS and get the minified version in seconds, with live before-and-after size statistics.

Minification (also called CSS compression) strips characters the browser ignores anyway, so the page renders identically while the stylesheet downloads and parses faster. It is different from gzip or Brotli compression, which your web server applies on top — and the two stack for the smallest transfer size. To make minified CSS readable again, use the CSS Beautifier.

Everything runs in real time and entirely in your browser — there is no signup, no upload, and your stylesheets never leave your device. Paste compact or messy CSS and watch the minified output update as you type.

Live Example

Here is a small stylesheet before and after minification. The styles are identical — only the comments, indentation, and extra spacing are removed:

Input (formatted)

/* Button styles */
.btn {
  display: inline-block;
  padding: 10px 20px;
  background-color: #007bff;
  color: #ffffff;
}

Output (minified)

.btn{display:inline-block;padding:10px 20px;background-color:#007bff;color:#ffffff}

How to Use CSS Minifier

Open the tool: Click Try It to launch the two-pane editor.
Paste Your CSS: Enter or paste the stylesheet you want to compress into the input area on the left.
Minify Automatically: The tool instantly strips comments, whitespace, and redundant separators while preserving your selectors and values.
Review Savings: Check the original size, minified size, and percentage saved shown above the output.
Copy or Download: Copy the minified CSS to your clipboard or download it as a .css file for your build.

Key Features

Removes comments and whitespace: strips /* ... */ comments, line breaks, and indentation that the browser does not need.
Collapses redundant separators: drops the spaces and trailing semicolons around { }:; and ,.
Preserves string values: content inside quotes is protected, so font names, content text, and URLs are never mangled.
Live compression statistics: see the original size, minified size, and percentage saved in real time.
Copy or download: grab the minified CSS to your clipboard or save it as a .css file.
100% private & client-side: everything runs in your browser — nothing is uploaded or stored.

Common Use Cases

Production optimization: Compress stylesheets before deploying to reduce bandwidth and improve load times.
Core Web Vitals: Shrink CSS weight to speed up render and boost your Largest Contentful Paint score.
Inlining critical CSS: Minify a small critical stylesheet before embedding it in the <head> for a faster first paint.
Email and widget CSS: Minify CSS used in HTML email or embedded widgets to keep payloads small.
Code cleanup: Remove leftover comments and formatting from generated or hand-written CSS.

About CSS Minification

CSS minification removes characters a browser does not need to interpret a stylesheet: comments, runs of whitespace, indentation, and the optional semicolons and spaces around declarations. Because browsers ignore these, the rendered result is unchanged — but the file is smaller, so it transfers over the network faster and parses more quickly. That is why production builds of almost every framework run a CSS minifier (like cssnano or clean-css) automatically as part of the bundling step.

Minification is not the same as gzip or Brotli compression. Minification shrinks the source text; the server then compresses the minified result further over the wire. Applying both gives the smallest payload. A safe minifier never removes characters that are significant: it preserves the spaces inside values like margin: 0 auto or border: 1px solid red, and it keeps the content of quoted strings intact so font-family lists, content properties, and url() references survive unchanged.

What a Minifier Removes

A typical CSS minifier targets four kinds of dispensable text:

Comments:/* ... */ blocks carry no meaning to the browser and are stripped entirely.
Whitespace: newlines, tabs, and multiple spaces collapse to nothing or a single significant space.
Trailing semicolons: the last ; before a closing } is optional and removed.
Separator spaces: spaces around { }:;, and combinators are dropped.

Minify vs Beautify vs Gzip

Minification and beautification are opposites: the CSS Beautifier re-adds indentation to minified CSS so a human can read it, while the minifier does the reverse for performance. Neither is the same as gzip, which compresses bytes on the wire and is undone by the browser. For the markup side of a page you can apply the same idea with the HTML Minifier, and for data payloads use the JSON Minifier. Stack minification with server-side compression for the smallest possible transfer size.

Common CSS Minification Issues & How to Fix Them

Descendant pseudo-class selector changed: a selector like a :hover (any hovered descendant of a) can collapse to a:hover (a when hovered) when spaces around : are removed. If the distinction matters, write the combinator explicitly or minify that rule by hand.
Value spaces flattened: this tool preserves significant spaces inside values (margin: 0 auto stays intact). If a minifier ever merges them, the layout can break — use one that guards quoted strings and value whitespace.
Comments removed: minification strips /* ... */ comments. If you need a license header or a comment to survive, keep an un-minified source copy and re-add it after minifying.
No size savings: if the CSS was already minified, there is nothing left to remove. Feed it formatted source to see real savings.
Source maps missing: a minifier shrinks names and structure, so debugging the live output is hard. Generate a source map in your build pipeline to map errors back to the original CSS.

Benefits of Using Our Tool

✅ Free to use with no registration required
✅ Instant, real-time minification
✅ Preserves CSS structure and functionality
✅ Clear before-and-after size statistics
✅ Private — all processing happens in your browser

Related Tools

Pair this minifier with its counterpart and the rest of our formatting and compression utilities:

CSS Beautifier — re-format minified CSS into readable, indented stylesheets.
HTML Minifier — compress your markup the same way for smaller pages.
HTML Beautifier — pretty-print minified HTML for review and debugging.
JSON Minifier — shrink JSON data payloads for smaller transfers.
HTML Tryit Editor — test your HTML, CSS, and JavaScript live in the browser.

Frequently Asked Questions

1What does a CSS minifier do?

A CSS minifier removes comments, whitespace, line breaks, and redundant separators from your stylesheet to reduce its file size while keeping the styles identical.

2How much can I reduce my CSS file size?

Reduction depends on how much formatting your CSS has, but typically you can save 10-40% of the original size. Already-minified CSS shows little further savings.

3Does minification change how my page looks?

No. Minification only removes characters the browser ignores, so your styles render exactly the same — the file is just smaller and faster to download.

4Is my CSS uploaded to a server?

No. Minification runs entirely in your browser, so your CSS never leaves your device and stays completely private.

5Will minification break my font names or content values?

No. The tool protects quoted strings, so font-family lists, content properties, and URL references keep their internal spaces and punctuation intact.

6What is the difference between minify and gzip?

Minification shrinks the CSS source text, while gzip or Brotli compresses the bytes on the wire. The two stack — minify first, then let your server compress for the smallest transfer size.

7Can I download the minified CSS?

Yes. After minifying, you can copy the result to your clipboard or download it as a .css file for use in your build.

8Should I minify descendant pseudo-class selectors like 'a :hover'?

Be careful. Removing the space can change 'a :hover' (any hovered descendant of a) into 'a:hover' (a when hovered). Write such combinators explicitly or minify that rule by hand.

9Does it work on mobile?

Yes, the CSS Minifier is fully responsive and runs in any modern browser on desktop, tablet, and mobile.