A design system, not a colour picker
Most platforms give you a logo slot and one accent colour. This is the full token set the product itself is built on — surfaces, text, borders, charts, sidebar — in both light and dark, plus type and corner radius. Start from a preset or tune every token.
Contrast is checked as you edit, and can be repaired automatically to WCAG AA — so a brand colour can never leave your own staff unable to read the screen.