An accessible color palette editor for creating branded palettes built from the ground up that pass WCAG/APCA contrast rules (which is much quicker and less of a headache compared to doing manual contrast checks and fixes later):

https://www.inclusivecolors.com/

The current web tool lets you export to CSS, Tailwind and Figma, and uses HSLuv for the color picker. HSL color pickers that most design tools like Figma use have the very counterintuitive property that the hue and saturation sliders will change the lightness of a color (which then impacts its WCAG contrast), which HSLuv fixes to make it much easier to find accessible color combinations.

I'm working on a Figma plugin version so you can preview colors directly on a Figma design as you make changes. It's tricky shrinking the UI to work inside a small plugin window!