Just Color Picker - Free portable colour picker and colour editor for web designers, photographers, graphic designers and digital artists. Supports Windows and macOS.
Sketch - Professional digital design for Mac.
Instant Eyedropper - Identifying the color code of an object on the screen is usually an involved, multistep process:...
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
gcolor2 - GTK+2 Color Selector
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.