Connect for ECMAScript

Connect is a family of libraries for building type-safe APIs with different languages and platforms. @connectrpc/connect brings them to TypeScript, the web browser, and to Node.js.

With Connect, you define your schema first:

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

And with the magic of code generation, this schema produces servers and clients:

const answer = await eliza.say({ sentence: "I feel happy." });
console.log(answer);
// {sentence: 'When you feel happy, what do you do?'}

Unlike REST, the Remote Procedure Call are type-safe, but they are regular HTTP under the hood. You can see all requests in the network inspector, and you can curl them if you want:

curl \
    --header 'Content-Type: application/json' \
    --data '{"sentence": "I feel happy."}' \
    https://demo.connectrpc.com/connectrpc.eliza.v1.ElizaService/Say

Connect uses Protobuf-ES, the only fully-compliant Protobuf JavaScript library.

Connect implements RPC three protocols: The widely available gRPC and gRPC-web protocols, and Connect's own protocol, optimized for the web. This gives you unparalleled interoperability across many platforms and languages, with type-safety end-to-end.

Follow our 10 minute tutorial where we use Vite and React to create a web interface for ELIZA.

React, Svelte, Vue, Next.js and Angular are supported (see examples), and we have an expansion pack for TanStack Query. We support all modern web browsers that implement the widely available fetch API and the Encoding API.

Follow our 10 minute tutorial to spin up a service in Node.js, and call it from the web, and from a gRPC client in your terminal.

You can serve your Connect RPCs with vanilla Node.js, or use our server plugins for Fastify, Next.js, and Express. We support Node.js v18.14.1 and later with the builtin http and http2 modules.

If you are migrating from v1 to v2, check out our migration guide;

Would you like to use Connect on other platforms like Bun, Deno, Vercel’s Edge Runtime, or Cloudflare Workers? We’d love to learn about your use cases and what you’d like to do with Connect. You can reach us either through the Buf Slack or by filing a GitHub issue and we’d be more than happy to chat!

• @connectrpc/connect: RPC clients and servers for your schema (source code).
• @connectrpc/connect-web: Adapters for web browsers, and any other platform that has the fetch API on board.
• @connectrpc/connect-node: Serve RPCs on vanilla Node.js servers. Call RPCs with any protocol.
• @connectrpc/connect-fastify: Plug your services into a Fastify server.
• @connectrpc/connect-next: Serve your RPCs with Next.js API routes.
• @connectrpc/connect-express: Adds your services to an Express server.

The libraries and the generated code are compatible with ES2017 and TypeScript 4.9.5.

• examples-es: Examples for using Connect with various TypeScript web frameworks and tooling
• connect-query-es: TypeScript-first expansion pack for TanStack Query that gives you Protobuf superpowers
• connect-playwright-es: Playwright tests for your Connect application
• connect-swift: Idiomatic gRPC & Connect RPCs for Swift
• connect-go: Go implementation of gRPC, gRPC-Web, and Connect
• examples-go: Example RPC service powering https://demo.connectrpc.com and built with connect-go
• conformance: gRPC-Web and Connect interoperability tests
• Buf Studio: web UI for ad-hoc RPCs

Offered under the Apache 2 license.