CSS Minifier
Compress, beautify, validate and analyze CSS in an IDE-style editor with safe minification, optimization presets, stylesheet analysis, before/after comparison, performance insights, bulk processing and export. Free and private.
What is the CSS Minifier?
A CSS Minifier removes everything a browser doesn't need to apply your styles — comments, whitespace, indentation and redundant characters — so stylesheets download and parse faster without changing how the page looks. Toollyz CSS Minifier is a complete optimization workspace, not just a compressor: an IDE-style editor with CSS syntax highlighting and line numbers, safe minification, and Safe, Aggressive and Conservative presets. It can lowercase and shorten hex colors (#ffffff → #fff), strip units from zero values, remove empty rules and preserve /*! license */ banners, beautify minified CSS back into readable form, and validate your stylesheet for unbalanced braces and unterminated comments or strings. A live before/after comparison, an analytics dashboard (bytes saved, compression percentage, optimization score, estimated load-time savings) and a stylesheet analysis (rules, selectors, declarations, media queries, colors) give real insight, plus bulk processing for many files at once. Crucially, the minifier never collapses a descendant-combinator space or alters calc() spacing, so it can't break your layout — and everything runs in your browser, so your code is never uploaded.
How to use it
- Paste, type or drop a CSS file into the editor — it minifies and validates as you type.
- Pick a preset (Safe, Aggressive or Conservative) or fine-tune each option in the Settings tab.
- Review the live output, before/after comparison, stylesheet analysis and size savings.
- Copy the minified CSS or download it — or drop several files into the Bulk tab to optimize them together.
Benefits
- Safe minification that never breaks layout — descendant combinators and calc() spacing are preserved.
- Safe, Aggressive and Conservative presets for one-click optimization.
- IDE-style editor with CSS syntax highlighting, line numbers and code-style typography.
- Lowercase & shorten hex colors, strip zero units, remove empty rules and keep license banners.
- Beautify minified CSS back to readable form with 2-space, 4-space or tab indentation.
- Validation for unbalanced braces and unterminated comments or strings, with line numbers.
- Analytics & stylesheet analysis — size reduction, optimization score, rules, selectors, colors.
- Before/after comparison, diff, bulk processing and instant export — 100% private in your browser.
Frequently asked questions
What is a CSS minifier?
A CSS minifier removes characters that aren't needed to render styles — comments, whitespace, indentation and redundant punctuation — to produce a smaller stylesheet that downloads and parses faster. Toollyz CSS Minifier also beautifies, validates, compares and analyzes your CSS.
How does CSS minification work?
The tool scans your stylesheet and re-emits it without unnecessary bytes: it collapses whitespace, drops comments, removes the last semicolon before a closing brace and can shorten colors and zero units. You choose how aggressive to be with presets or individual toggles.
Will minifying break my CSS?
No. The minifier is whitespace-aware: it never removes the space in a descendant combinator (.a .b is kept distinct from .a.b) and never alters the operator spacing inside calc(). The Safe preset only removes bytes that don't affect rendering; the Aggressive preset adds opt-in transforms you can preview before shipping.
Can I beautify CSS again after minifying?
Yes. Click Beautify to pretty-print minified or messy CSS with clean, consistent indentation (2 spaces, 4 spaces or tabs) and one declaration per line. You can switch between minify and beautify freely, with full undo/redo.
Does it shorten hex colors and remove units?
Yes. Enable “Shorten hex colors” to collapse #ffffff to #fff (only when safe) and “Lowercase hex colors” to normalize them. The Aggressive preset also strips units from zero values (0px → 0) for length units outside calc().
Can I keep license comments?
Yes. With “Preserve license comments” on (the default), /*! … */ and @license banners are kept even while all other comments are removed — so legal notices survive minification.
Can I upload or batch-process CSS files?
Yes. Drag a single file onto the editor to load it, or drop several files into the Bulk tab to minify them all at once with your current settings, with per-file savings and one-click download.
Does it validate my CSS?
It performs structural validation — flagging unbalanced braces or parentheses and unterminated comments or strings with line numbers — so you can catch the mistakes that most often break a stylesheet before you ship it.
Is my CSS stored online?
No. All scanning, minification, validation and analysis happen entirely in your browser — your CSS is never uploaded to any server. Saved sessions live only in your device's local storage.
Does it work on mobile?
Yes. The editor, settings, analytics, validation, comparison and bulk tools are fully responsive and touch-friendly, so you can optimize CSS on any device.
Is this CSS minifier free?
Completely free with no signup and no limits. Minification, beautifying, validation, analytics, comparison, bulk processing and exports are all available to everyone, privately in your browser.