I have just finished the first version of Visual Source. It's a local GUI you can spin up in your projects which allows you to manage your design tokens (e.g. color palettes, variables).
As you make changes in Visual Source we generate a CSS file you can import which contains all of your defined tokens. When using a development server like vite you will see the changes in your app immediately.
I've been using this for a bunch of my own projects for a while now and am interested to see what others take is on this approach! I've found it a lot more ergonomic than writing my CSS variables by hand. Any feedback or questions welcome.