ChromaCheck

Simulate color blindness and run WCAG contrast audits on any webpage. Catch accessibility issues before your users do.

ChromaCheck shows you what your website looks like to the 300 million people worldwide with color vision deficiency — and tells you exactly where your design is failing them. ━━━ SIMULATE REAL VISION ━━━ Apply scientifically calibrated filters to any webpage to see it through seven types of color blindness: • Green weak (Deuteranomaly) — the most common form, ~5% of men • Red weak (Protanomaly) • Green blind (Deuteranopia) • Red blind (Protanopia) • Blue weak (Tritanomaly) • Blue blind (Tritanopia) • No color vision (Achromatopsia) Plus a high-contrast assistive view for low-vision users. The simulation uses the Brettel-Viénot-Mollon (1997) and Machado et al. (2009) color projection models — the same math used in vision research. Not a tinted overlay, not a guess. The real perceptual transform. ━━━ AUDIT WHAT MATTERS ━━━ One click runs a full WCAG 2.1 contrast audit on every text element on the page: • AAA, AA, and A compliance counts • Overall compliance percentage • Specific failing elements with selectors, ratios, and text snippets • Click any failure to scroll directly to it on the page ━━━ CATCH WHAT OTHER TOOLS MISS ━━━ ChromaCheck's killer feature: it re-runs the contrast audit through each color blindness projection and flags regressions — pairs that pass for normal vision but fail under deuteranopia, protanopia, or tritanopia. This is where most accessibility issues actually live. A red-on-green "required field" indicator that looks fine to you might be invisible to the colorblind reviewer on your team. ChromaCheck finds those before they ship. ━━━ FAST AND PRIVATE ━━━ • Audits run locally in your browser. No data leaves your machine. • No accounts, no telemetry, no network requests. • No host permissions — only touches a tab when you click the icon. • Open source. ━━━ WHO IT'S FOR ━━━ • Designers and developers shipping accessible interfaces • Accessibility specialists auditing sites • Product managers reviewing what users with CVD actually experience • Anyone curious how their friend, parent, or colleague sees the web About 1 in 12 men and 1 in 200 women have some form of color vision deficiency. They're using your site right now. ChromaCheck helps you make sure they can.