WhoCanUse checks a foreground/background color pairing and shows the WCAG contrast ratio and grade alongside simulated previews for moderate and severe color blindness, plus low vision conditions like cataracts and glaucoma.
Rather than a single pass/fail contrast number, it shows what percentage of the population would actually struggle with a given pairing and previews the combination through several different visual conditions at once, making the real-world impact concrete instead of abstract.
Designers and developers who want to see how a color pairing actually looks to people with different visual impairments, not merely get a numeric contrast score.
Test pairings against more than just deuteranopia (red-green). The low-vision simulations (cataracts, glaucoma) catch different problems than a colorblindness check alone.
Understand how color contrast affects people with visual impairments.
