AspNetCore.Proxy VS ProxyKit

By setting up your backend as a proxy to another API, you're setting up extra code: your front end makes a request to your back end, and your back end makes an almost identical request to another API, which means more code to maintain and more unit tests to write. A lot of the code duplication goes away if you use a package like AspNetCore.Proxy to do most of the heavy lifting with implementing a proxy.

Worth noting that YARP (or as someone has eloquently described it as PRAY) here was another Microsoft project which basically killed a previous open source project which did the same thing:

https://github.com/proxykit/ProxyKit

This actually feels like one of the instances that PeachPie with a combination of ProxyKit or YARP would be handy.

You could setup a proxy with ProxyKit in you WebHost. Your blazor app will send requests to, say http://webhost:5000/api/endpoint. The host will then forward the request to http://webapi:3000/endpoint (or whatever). You'll have to setup some kind of JWT authentication where the WebHost generates a JWT on login and saves it in the cookie. Good thing here is, the cookie really only contains some id the server uses to look up the actual contents of the cookie. Only the cookie gets returned to the browser (blazor app). On each api request, the webhost will fetch the token out of the server-side cookie and append it to the Authorization header. The webapi will validate the token and return the response that will be proxied back to your front-end.