I made this app as I generally like the built-in color picker on macOS, but I could only use it from inside certain apps. I also added some features I need all the time, like being able to copy-paste colors in various formats.
The app is very customizable with a bunch of preferences. For example, you could put it in the menu bar, and show the color sampler with a global keyboard shortcut, and then have the color copied to the clipboard after picking.
The app is open source on GitHub.
– Sindre Sorhus