Scores every pair of colors in a palette you already have by its worst-case separation across all four simulated deficiencies, worst pair first, and names the one that limits each. When pairs fail, Suggest fixes nudges the fewest colors the least distance until every pair clears the floor.
Checks the WCAG 2.x contrast ratio between a foreground and background color — legibility for anyone, independent of any simulated deficiency above. A color pair can score well here and still be a poor pick under a deficiency, or the reverse, since contrast ratio measures luminance while the confusion scores above measure hue and saturation.
Images are processed entirely in your browser — nothing is uploaded anywhere. The sample image pairs colors people often confuse under each deficiency (reds and greens, blues and yellows) alongside a full hue gradient. Click either image to inspect that exact pixel's original and displayed color (see below).