WCAG 2.1 Color Contrast Checker
Verify text and UI color combinations against WCAG 2.1 Level AA and AAA accessibility standards.
Execution runs 100% locally inside the browser sandbox using HTML5 Canvas, Web Cryptography Subtle API, and Web Workers. No data is ever transmitted across the network.
Zero network latency. Operates completely offline with zero dependencies on third-party backend servers or cloud services.
Built according to official RFC specifications, cryptographic test vectors, and enterprise-grade data transformation standards.
How to Use WCAG 2.1 Color Contrast Checker
Pick foreground text color and background canvas color.
Review the numerical contrast score (e.g. 4.5:1, 7.0:1).
Confirm pass/fail ratings across normal, large, and UI elements.
Frequently Asked Questions
What is the minimum WCAG AA ratio for normal text?
WCAG 2.1 Level AA requires a minimum contrast ratio of 4.5:1 for body text (under 18pt regular / 14pt bold).
What is required for large text?
Large text (18pt+ or 14pt+ bold) requires a minimum ratio of 3.0:1 for Level AA.
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