Minify CSS online to reduce stylesheet file size and speed up page load times. This free browser tool strips comments, whitespace, and redundant characters from your CSS without altering the actual styles. No signup or upload required, paste your stylesheet, minify it, and paste the result directly into your project or deployment pipeline.
The CSS Minifier compresses CSS code by removing all whitespace, comments, and redundant characters without changing how the styles are applied. Smaller CSS files load faster, which directly impacts page rendering performance and Core Web Vitals scores, particularly the First Contentful Paint metric. The minifier removes newlines, spaces around selectors, colons, semicolons, and braces, strips single-line and multi-line comments, removes the last semicolon in a declaration block (it is optional), and merges adjacent rules where possible. The tool shows original and compressed file sizes and the compression percentage. You can toggle whether to preserve certain comment types, such as license comments that start with /*! which should typically be kept in production. All processing runs in your browser and your CSS is not sent to any server.
CSS minification is standard practice in production web deployments. Even stylesheets that start at 50KB can often be reduced to 30KB or less, which is meaningful for users on slower connections. Modern build tools (Webpack, Vite, Parcel, Rollup) minify CSS automatically during production builds using tools like cssnano or Lightning CSS, but there are situations where manual minification is useful: embedding a small style block in an email template where size limits are strict, preparing a CSS snippet for a CDN without a build pipeline, or analyzing the compressed size of a third-party stylesheet. Beyond whitespace removal, advanced CSS minification includes removing duplicate rules, shortening color values (#ffffff to #fff, rgb(255,0,0) to red), converting long-form properties to shorthand (margin-top, margin-right, margin-bottom, margin-left to a single margin value), and removing browser-prefixed properties that are no longer needed. This tool performs whitespace and comment removal, which typically achieves 20 to 35 percent reduction on typical stylesheets. For critical CSS (the styles needed to render above-the-fold content), minification and inlining it in the HTML head eliminates a render-blocking external stylesheet request entirely, significantly improving perceived load speed. Always keep your original unminified source in version control since minified CSS is not human-editable.