See how colors appear under common types of color blindness. Check if two colors stay distinct.
These are standard approximations of how color vision deficiencies shift colors. They are useful for spotting problem pairs (e.g. red/green that collapse to the same shade), not a clinical diagnosis.
It takes two colors and shows how each one looks under the common color vision deficiencies: protanopia, deuteranopia, tritanopia and full achromatopsia. If the two swatches become indistinguishable in a row, that color pair is a problem for those users.
Roughly 1 in 12 men has some color blindness. Charts, status colors and links that rely on red versus green can be unreadable for them. Checking pairs here helps you pick accessible combinations or add non-color cues.
They are widely used approximations, good for catching issues during design. They are not a medical assessment of any individual's vision.