I'm happy to share the code, but realistically I'm unlikely to add features. There are already so many colour pickers that I didn't see the point in adding that functionality.

I created the tool while putting together a couple blog posts on how to use colours effectively in data visualizations. There are a number of links in those posts to other pickers out there: https://briancort.com/?p=146 https://briancort.com/?p=174