Pika is described as '(pronounced pi·kuh, like picker) is an easy to use, open-source, native colour picker for macOS. Pika makes it simple to quickly find colours on screen, in the format you need, so you can get on with being a speedy, successful designer' and is an app in the Photos & Graphics category. There are more than 50 alternatives to Pika for a variety of platforms, including Windows, Mac, Online / Web-based, Linux and iPhone. The best alternative is Microsoft PowerToys, which is both free and Open Source. Other great apps like Pika are Just Color Picker (Free), gpick (Free, Open Source), Instant Eyedropper (Free, Open Source) and gcolor2 (Free, Open Source).
Instant Eyedropper is a free color detection tool for webmasters that will identify and automatically paste to the clipboard the HTML color code of any pixel on the screen with just a single mouse click.
gcolor2 is a basic colourpicker utility that allows you to select any colour on your screen, and, well, grab it's colour. It also allows you to save the colour you create to a file, which shows up as a list in the application.
The refreshingly simple color picker for developers that instantly samples and encodes any color on your screen. Just one quick click to savor the flavor and you're set! See what’s on special with Sip below.
Colorpicker is efficient through its interface. Every features are accessible from the toolbar and shortcuts. You have the possibility to choose any color thanks to the three RGB sliders (soon HSL, CMYK, ...)!