Free CSS/JS Minifier Online

Every kilobyte of CSS and JavaScript on your page costs something — bandwidth on slow mobile networks, parse time on weaker devices, paint delay on first render, and a measurable hit to Core Web Vitals scores that directly affect your Google search ranking. Minification removes that overhead by stripping comments, collapsing whitespace, shortening variable names, and removing unnecessary syntax — typically reducing CSS by 20-50% and JavaScript by 30-70% with zero functional change. Our free online CSS and JavaScript minifier handles both languages in one tool. Paste your code, click Minify, copy the optimised output. Use it the other direction too: paste minified code (vendor libraries, output from your build pipeline you need to debug, code copied from a production page) and click Beautify to restore readable formatting with proper indentation. For CSS, the minifier handles all standard syntax: selectors, properties, media queries, keyframe animations, CSS Custom Properties (CSS variables), and nested rules from preprocessors. For JavaScript, it handles ES6+ features (arrow functions, template literals, destructuring, classes, async/await, modules) while preserving correct semantics — no broken `for-of` loops, no mangled regex patterns, no semicolon-insertion bugs that you sometimes see with naive minifiers. Common workflows people run it for: minifying a hand-written CSS file before uploading to a static site host where build tooling is overkill, optimising a small JavaScript snippet for an embedded script tag where every byte matters, beautifying minified code from a third-party CDN for debugging or learning, preparing CSS/JS for inline embedding in HTML emails (where smaller is critical), and checking the actual size impact of code changes (the size comparison shows the exact byte savings). **Important context:** for serious production builds, your project bundler (Webpack, Vite, Rollup, esbuild, Parcel, Turbopack) almost certainly already includes minification as part of the build process, with smarter optimisations (tree-shaking dead code, scope hoisting, code splitting) than a single-file minifier can do. This tool fits the gap: small one-off minifications, hand-written code where setting up a build is overkill, and the reverse case of beautifying minified code for inspection. Everything runs in your browser — your CSS, JavaScript, source maps, and any sensitive code (API keys, internal logic, business rules) never travel to any server. Pair this with our [HTML Beautifier](/tools/html-beautifier) for HTML formatting, [CSS Minifier](/tools/css-minifier) for CSS-only workflows, [Code Beautifier](/tools/code-beautifier) for general code formatting, and [JSON Formatter](/tools/json-formatter) for JSON config files.