Color Blindness Simulator

Roughly 1 in 12 men and 1 in 200 women have some form of red-green colour vision deficiency, which makes it one of the most common accessibility considerations a design will actually run into in practice — and one of the easiest to check for directly, rather than guessing. This simulates eight named types: full protanopia, deuteranopia and tritanopia (a cone type entirely absent), their milder anomalous counterparts (a cone type present but weak, which is by far the more common real-world case), and achromatopsia and achromatomaly, the very rare forms with little or no colour perception at all.

Two modes cover the two things actually worth checking. Image mode takes a screenshot, mockup or photo and simulates the whole thing — the fastest way to spot a chart that only distinguishes its series by red versus green, or a status indicator that relies entirely on colour. Palette mode checks a specific set of colours directly — a brand palette, a design system's status colours — without needing a rendered screenshot at all.

The simulation uses the transformation matrices most browser-based colour blindness tools use, applied directly to sRGB values. That is a known simplification of the actual physiology — a rigorous simulation would work in linear light — but it is the standard, widely-used approximation for this exact purpose, and the difference is not the point: what matters is whether two colours that look distinct to typical vision still look distinct after the transform, and this answers that reliably enough to act on.