If you're developing an application based on React it can be helpful if you don't need to develop all the basic UI components yourself. Here you can find a list with various components, component libraries and complete design systems developed with and for React.
As the list got longer and longer I thought it would be better to have a "real" site for it.
That's true. I believe they start with vanilla components and add the React implementation later on.
I found one more from J.P. Morgan
https://www.saltdesignsystem.com/components/