https://x.com/seanw_org/status/1815442179361317022
There's lots of tools in this space, but the key features of this is it lets you easily check the contrast of any color pair (not just against white, so you can check e.g. your text colors will contrast on off-white shades), it's for creating a full palette of colors vs a handful of brand colors (you always end up needing lighter/darker variants for things like borders and backgrounds), and you can alter how the hue/saturation/lightness varies across a whole swatch of colors with a few clicks (being able to visualise these curves also makes picking new colors really easy).
Feel free to reach out if you think this might be useful to you!