Contrast – “A macOS app for quick access to WCAG (Web Content Accessibility Guidelines) color contrast ratios.  The Web Content and Accessibility Guidelines are provided as a means to create more accessible interfaces for all, especially those with visual impairment.  The entire app UI updates instantly when picking colors, making it easy to get the color contrast information you need to make informed decisions about the color of your text.  With this app, you can see the contrast score as soon as colors are picked. No more disrupting your design flow by going online to check contrast. You should really read the guide.