gRPC Request Builder

grpcurl is a command-line tool for interacting with gRPC servers, similar to curl for HTTP. It uses protobuf reflection or a .proto file to discover service methods and can send requests in JSON format. It's the fastest way to test gRPC endpoints without writing code.

gRPC uses HTTP/2 framing directly and is suited for server-to-server or native client communication. gRPC-Web is a browser-compatible protocol that works over HTTP/1.1 or HTTP/2 via a proxy (like Envoy). Browsers cannot use raw gRPC because they lack low-level HTTP/2 stream control.

In grpcurl, use the -H flag: `-H 'authorization: Bearer TOKEN'`. In Node.js @grpc/grpc-js, pass metadata as the second argument: `const meta = new grpc.Metadata(); meta.add('authorization', 'Bearer TOKEN'); client.Method(request, meta, callback)`.

A typical proto file starts with `package myapp.v1;` and then `service UserService { rpc GetUser (GetUserRequest) returns (GetUserResponse); }`. The fully-qualified method name used by grpcurl is `myapp.v1.UserService/GetUser`.

Yes — if the server has reflection enabled (most dev servers do), grpcurl can introspect services at runtime without any proto files using `-proto` flag or reflection. In production, reflection is often disabled for security, so you'd need the .proto file or a generated descriptor set.