A tool for generating colour palettes which are perceptually consistent in terms of lightness, contrast, and saturation. Usefully, it automatically calculates WCAG 2 contrast ratios; it also attempts to guess at WCAG 3 scores, though this remains an unknown in terms of how it will ultimately be applied (it is useful to sanity check perceived contrast versus calculated contrast, though). You can also modify the underlying colour space per colour, and set hue shifts, to stop colours morphing across the calculated gradient (e.g. prevents blues from becoming too purple, or yellows turning too green). In other words, a very powerful colour calibration tool.