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CSS Compressor

Minify CSS by stripping comments and whitespace to shrink your stylesheet's size.

Related tools

All Colours & CSS tools →
CSS Box Shadow GeneratorDial in a CSS box-shadow with live preview and copy the generated code — offset, blur, spread, color, inset.CSS Flexbox PlaygroundExperiment with flex-direction, wrap, justify-content, align-items and gap — live preview and copyable CSS.CSS Grid GeneratorBuild a CSS grid layout visually — columns, rows, gaps and alignment — with a live preview and copyable CSS.HTML CompressorMinify HTML by removing comments and collapsing whitespace to reduce page weight.CSS BeautifierReformat minified or messy CSS into clean, properly indented rules — or minify it back.Color Contrast CheckerWCAG contrast ratio between text and background, with AA/AAA pass-fail and a live preview.Color InverterInvert a colour (255 − RGB) or take its complement, in HEX/RGB/HSL/CMYK with the contrast between them.Color Scheme GeneratorDerive complementary, analogous, triadic, tetradic, split and monochromatic schemes from a base colour.

CSS Compressor is free to use as often as you like, directly from this page. It sits under Colours & CSS in our catalogue, alongside CSS Box Shadow Generator and CSS Flexbox Playground.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does CSS Compressor do?

Minify CSS by stripping comments and whitespace to shrink your stylesheet's size.

When would I actually use this?

Moving a colour between a design tool and a stylesheet, building a palette around one brand colour, and checking text will be readable on it.

What is the most common mistake?

Judging contrast by eye. Two colours that look distinct on a bright monitor can fail the accessibility ratio outright, and the ratio is the thing an audit will measure.

How is CSS Compressor different from CSS Box Shadow Generator?

They sit next to each other but answer different questions. CSS Box Shadow Generator: dial in a CSS box-shadow with live preview and copy the generated code — offset, blur, spread, color, inset. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

CSS Flexbox Playground is the closest one after this: Experiment with flex-direction, wrap, justify-content, align-items and gap — live preview and copyable CSS.

What else is worth having open alongside it?

CSS Grid Generator and HTML Compressor — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Conversions between HEX, RGB and HSL are exact. Contrast follows the WCAG 2 relative-luminance formula; CMYK is device-dependent, so a screen value is an approximation of what will print.

Further reading

All guides →
GuideWhat a Minifier Can Remove, and What It Must NotMinification has to preserve meaning, and the interesting part is the whitespace that carries meaning: the descendant combinator, the spaces inside calc(), the gap between two inline elements. Measured here on real files, including how much brotli was going to save you anyway.GuideBeautify or Minify: What Each Is For, and What It Does to the WeightFour real stylesheets run through the minifier, measured raw and after gzip. Stripping every space saved 48, 103, 104 and 147 compressed bytes; stripping comments saved 57, 1 358, 2 420 and 1 042. Plus the five inputs this minifier breaks.ExplainerGradients, Banding, and Why the Middle Looks MuddyInterpolating in sRGB averages gamma-encoded numbers, so the midpoint of red to green is #808000 when the half-light answer is #bcbc00 — 57.2% too little light. Banding is a separate arithmetic problem: 8 bits give 256 steps, and a dark gradient may have only 28 of them. Here is both, computed.ExplainerColour Schemes Are Geometry on a Wheel — and the Wheel Is WrongComplementary, triadic, analogous and split-complementary are just rotations: add 180°, 120°, 30° or 150° to a hue. The arithmetic is trivial. The problem is that the HSL hue circle is not perceptually uniform — yellow and blue at the same HSL lightness differ in luminance by 12.85 times — so a generated palette has to be contrast-checked afterwards.ExplainerContrast Ratio: How WCAG Actually Computes ItThe WCAG ratio is (L1 + 0.05) ÷ (L2 + 0.05), and L is relative luminance, not brightness. Green carries 71.52% of it and blue 7.22%, which is why pure blue on white passes at 8.59:1 while mid grey fails at 3.95:1. Here is the whole computation, run end to end.How-toHEX vs RGB: How to Read and Convert ColoursHEX and RGB are two notations for the same colours. Here's how to read each, convert between them, and add transparency.