Color Contrast & Perception Checkers: The Best Free Tools
If the text on your site is hard to read, you're losing visitors - and you may be failing accessibility law. A color contrast checker measures the difference between your text color and its background, while a color perception checker simulates how your design looks to people with color blindness. Both are quick ways to catch readability problems before they cost you.
Why color contrast matters
Around 1 in 12 men and 1 in 200 women have some form of color vision deficiency, and far more people simply struggle with low-contrast text - on a phone screen in bright sunlight, for example. The Web Content Accessibility Guidelines (WCAG) 2.2 set minimum contrast ratios: 4.5:1 for normal text and 3:1 for large text at the AA level most laws require.
Hitting those ratios isn't just compliance box-ticking - higher contrast measurably improves readability and conversions for everyone.
The best free color contrast & perception checkers
- WebAIM Contrast Checker - the go-to tool. Enter a foreground and background color and it instantly shows the contrast ratio and whether it passes WCAG AA and AAA for normal and large text.
- TPGi Colour Contrast Analyser (CCA) - a free downloadable app for Windows and Mac. It includes an eyedropper to sample any color on your screen and a color-blindness simulator.
- Toptal Colorblind Web Page Filter - enter a URL and it shows how your live page looks under different types of color blindness, so you can spot information that relies on color alone.
How to use them
Start by running your main text and button colors through a contrast checker and adjusting any combination that falls below 4.5:1. Then view your key pages through a color-perception simulator to make sure nothing important - error messages, links, chart legends - is distinguishable only by color. Pair color with text, icons, or underlines so the meaning survives for everyone.
For a fuller toolkit, see our 80+ web accessibility resources and tools.