That is great thanks! I'm trying to see if there is one that lets you manage client uploads with a token, i.e. the server gives an "upload token" to the client

That is great thanks! I'm trying to see if there is one that lets you manage client uploads with a token, i.e. the server gives an "upload token" to the client so an "untrusted client" has permission to upload a file on behalf of the server, but without having to send the file to the server. Do you know off the top of your head if any CDN provides this?