Contraste is described as 'allows you to quickly know if a combination of colors, for a text and a background, passes accessibility thresholds defined by the W3C, and thus is accessible to users with visual impairements' and is an app in the OS & Utilities category. There are four alternatives to Contraste for Mac. The best alternative is Contrast – Color Accessibility. Other great apps like Contraste are Pochade (Paid), Color Picker Pro (Paid) and Pikka (Paid).
Pochade easily allows you to select any color from your screen, save your collection of colors, and get the color value the way you want. Pochade is ideal for anyone that often has to get different color values from their screen.