It's a compatibility layer for projects already built on @grpc/grpc-js. The generated clients and servers plug into your existing gRPC channels and servers, but serialize Protobuf-ES messages directly. This lets you upgrade to a better Protobuf package without touching your RPC stack.

[!TIP] For new projects, use Connect-ES instead. Connect speaks the gRPC and gRPC-Web protocols in addition to its own, so existing gRPC clients can call a Connect server unchanged. But you also get plain HTTP APIs you can curl, first-class streaming, and generated clients for every major language, including your frontend. protoc-gen-grpc-es only exists so current gRPC codebases already built on @grpc/grpc-js can get the improvements of Protobuf-ES today without a full rewrite.

Getting started

Installation

To install the runtime libraries and the protoc plugins, run:

npm install @bufbuild/protobuf @grpc/grpc-js
npm install --save-dev @bufbuild/protoc-gen-es @bufbuild/protoc-gen-grpc-es @types/node

Generating code

We recommend using buf to generate code. Add a new buf.gen.yaml configuration file:

# Learn more: https://buf.build/docs/configuration/v2/buf-gen-yaml
version: v2
inputs:
  - directory: proto
plugins:
  - local: protoc-gen-es
    out: src/gen
    opt: target=ts
  - local: protoc-gen-grpc-es
    out: src/gen
    opt: target=ts

Place your .proto files in the ./proto directory, then run:

npx buf generate

Usage

For every Protobuf file that contains services, the plugin generates a _grpc.ts file next to the _pb.ts file from protoc-gen-es. For example, the following service:

syntax = "proto3";
package example;

service ElizaService {
  rpc Say(SayRequest) returns (SayResponse);
}

message SayRequest {
  string sentence = 1;
}

message SayResponse {
  string sentence = 1;
}

generates the following exports in eliza_grpc.ts:

• ElizaServiceDefinition: The @grpc/grpc-js service definition.
• ElizaServiceServer: An interface for the server implementation.
• ElizaServiceClient: A client with a typed method for every RPC.

To implement a server:

import * as grpc from "@grpc/grpc-js";
import { ElizaServiceDefinition, type ElizaServiceServer } from "./gen/eliza_grpc.js";

const implementation: ElizaServiceServer = {
  say(call, callback) {
    callback(null, { sentence: `You said: ${call.request.sentence}` });
  },
};

const server = new grpc.Server();
server.addService(ElizaServiceDefinition, implementation);
server.bindAsync("localhost:50051", grpc.ServerCredentials.createInsecure(), () => {});

To call it with a client:

import * as grpc from "@grpc/grpc-js";
import { ElizaServiceClient } from "./gen/eliza_grpc.js";

const client = new ElizaServiceClient("localhost:50051", grpc.credentials.createInsecure());
client.say({ sentence: "Hi" }, (error, response) => {
  if (error) {
    throw error;
  }
  console.log(response?.sentence);
});

Plugin options

protoc-gen-grpc-es supports the same options as protoc-gen-es:

Make sure to use the same target and import_extension values for both plugins, so that the generated _grpc files can import from the generated _pb files.