I'm still iterating on a WCAG accessible palette creator for web design/UI:

https://www.inclusivecolors.com/

I use it myself for making branded palettes for projects because it gives you full control over the hue, saturation and lightness curves (instead of these being mostly autogenerated), and it helps you make tint/shades for multiple swatches at a time that go together (rather than a single swatch at a time).

Get in touch if you have any feature requests!