CSS Minifier
Minify and compress CSS instantly online. Removes comments, collapses whitespace, and strips unnecessary characters. Free CSS minifier — no signup, runs entirely in your browser.
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CSS minification is the process of removing all characters that are not required for the stylesheet to function: whitespace, indentation, newlines, and comments are stripped, and optional spaces around selectors and property values are eliminated. The result is semantically identical to the original but significantly smaller, which reduces HTTP transfer size and parse time.
For production websites, minified CSS is standard practice. A typical well-written stylesheet might be 40–60% larger than its minified equivalent due to indentation and comments. Tools like webpack's css-minimizer-webpack-plugin, PostCSS, and build steps in frameworks like Next.js and Vite perform this transformation automatically; this tool lets you do it manually for quick testing or for projects without a build pipeline.
This tool performs safe, comment-stripping minification in the browser using pure JavaScript: it removes /* */ comment blocks, collapses sequences of whitespace to a single space, and strips spaces adjacent to punctuation characters ({, }, :, ;, ,). It does not perform advanced optimization like merging duplicate rules or shorthand property conversion, which can sometimes change specificity or cascade behavior.
Common Use Cases
Optimizing stylesheets without a build tool
Static websites, WordPress child themes, and legacy PHP applications often lack a modern JavaScript build pipeline. Developers can write readable CSS during development, then paste it here before copying the minified version into the production stylesheet. The size reduction immediately improves Lighthouse performance scores and Core Web Vitals.
Measuring potential savings before tooling investment
Before committing to setting up PostCSS or a webpack configuration, a developer can paste their current CSS to see how many bytes would be saved by minification. If a stylesheet shrinks from 80 KB to 50 KB, the 37% reduction justifies the setup time for automated minification in the build process.
Preparing inline styles for HTML emails
HTML emails must use inline styles rather than external stylesheets because most email clients strip external CSS links. When converting a component's CSS to inline form, minifying the resulting style attribute values keeps the email HTML compact and within attachment size limits for providers like Gmail and Outlook.
Minifying CSS snippets for CodePen or Gist embeds
When sharing a minimal reproduction of a CSS layout issue on Stack Overflow, CodePen, or a GitHub Gist, pasting minified CSS keeps the code block concise and avoids line-count limits in forum post character limits. Reviewers can still inspect the styles; they are just presented without unnecessary whitespace.
How to Use the CSS Minifier
- Paste your CSS in the left panel.
- The minified output appears instantly with a size-saved percentage.
- Click "Copy Output" to copy the minified CSS to your clipboard.
- Use "Load Example" to see a sample minification.