In Blazor WebAssembly, like in all other browser-based single-page app (SPA) technologies, by far the most common way to exchange data and trigger server-side operations is JSON-over-HTTP. It’s simple: the client makes an HTTP request to some pre-agreed URL, with a pre-agreed HTTP method, sending JSON data in a pre-agreed shape, and then the server performs an operation and replies with a pre-agreed HTTP-status code and JSON data in a pre-agreed shape.
Read more: https://blog.stevensanderson.com/2020/01/15/2020-01-15-grpc-web-in-blazor-webassembly/