Use gRPC in browser apps

By James Newton-King

It's not possible to directly call a gRPC service from a browser. gRPC uses HTTP/2 features, and no browser provides the level of control required over web requests to support a gRPC client.

gRPC on ASP.NET Core offers two browser-compatible solutions, gRPC-Web and gRPC JSON transcoding.


gRPC-Web allows browser apps to call gRPC services with the gRPC-Web client and Protobuf.

  • Similar to normal gRPC, but it has a slightly different wire-protocol, which makes it compatible with HTTP/1.1 and browsers.
  • Requires the browser app to generate a gRPC client from a .proto file.
  • Allows browser apps to benefit from the high-performance and low network usage of binary messages.

.NET has built-in support for gRPC-Web. For more information, see gRPC-Web in ASP.NET Core gRPC apps.

gRPC JSON transcoding

gRPC JSON transcoding allows browser apps to call gRPC services as if they were RESTful APIs with JSON.

  • The browser app doesn't need to generate a gRPC client or know anything about gRPC.
  • RESTful APIs are automatically created from gRPC services by annotating the .proto file with HTTP metadata.
  • Allows an app to support both gRPC and JSON web APIs without duplicating the effort of building separate services for both.

.NET has built-in support for creating JSON web APIs from gRPC services. For more information, see gRPC JSON transcoding in ASP.NET Core gRPC apps.


gRPC JSON transcoding requires .NET 7 or later.

Additional resources