Contrast is a macOS app for designers and developers that provides quick access to WCAG color contrast ratios.
Skala Color is a compact and feature-rich macOS color picker that works with a huge variety of formats, covering everything you’re likely to need for web, iOS, Android, and macOS development — Hex, CSS RGBA, CSS HSLA, UIColor, NSColor and more.
If you see a beautiful color and you need its code to use it later in your projects, then "Kameleon - Color Picker for Pocket" is the app that you need. It is a very simple app that helps you pick and save colors from the real world and from your photos. Picking a color is now easier than ever.