Kontrast is a color contrast checker that tells you if your color combinations are distinct enough to be readable and accessible. It is part of the Plasma Mobile app collection.
WAVE is a visual web accessibility analysis tool that evaluates web accessibility based on the Web Content Accessibility Guidelines (WCAG).This app doesn't have any features at the moment.
Palette provides a super simple way to analyze colors across RGB, #HEX and CSS formats. Try it online for free or download it for macOS with a donation-based download where you pay what you want (even $0 to try it).