The large sample area allows to judge the selected colors comfortably.
Beside the background-color, you can select a foreground-color, this way you can see immediately, whether the colors are in harmony with each other.
Alter colors in the intuitive HSL system (Hue, Saturation, Luminance).
Make snapshots from the desktop, and afterwards pick the colors from the zoomed display.
You can save colors with drag&drop to user defined palettes.
There are several predefined color palettes with named colors.
Import and export color palettes to the GIMP (*.gpl), the Paint-Shop-Pro (*.PspPalette) and the Adobe-Swatch-Exchange (*.ase) format.
Generate color gradients and export them to CSS, the CSS template can be customized.
Choose between different formats of color codes, including the HTML-hex code and the RGB representation.
Info & Portable Download:
https://www.martinstoeckli.ch/colorbug/colorbug.html