Just Color Picker - Free portable colour picker and colour editor for web designers, photographers, graphic designers and digital artists. Supports Windows and macOS.
Color Palette Generator - Enter the URL of an image and find its color palette
ColorMania - Colormania is an advanced color picker utility, especially created
Materialette - A material design color palette on macOS / Windows / Linux
gpick - A color picker and color scheme creation tool.
Material Palette - Generate and export your Material Design color palette