Generate an OpenAPI spec from your tRPC server, in one line of code

Step 1: Install trpc-openapi-2

# npm
npm install trpc-openapi-2

# yarn
yarn install trpc-openapi-2

# pnpm
pnpm install trpc-openapi-2

Step 2: Generate OpenAPI spec

import { trpcToOpenApi } from "trpc-openapi-2";

// generate OpenAPI spec
const openApiSpec = trpcToOpenApi({
  apiTitle: "Your API",
  apiVersion: "1.0.0",
  basePath: "/trpc",
  router: trpcRouter,
});

// express example: serve openapi spec at /openapi.json
app.get("/openapi.json", (_, res) => res.json(openApiSpec));

Configuring the OpenAPI spec

Excluding certain procedures

Step 1: Add OpenApiMeta to your initTRPC call:

import { OpenApiMeta } from "trpc-openapi-2";

const t = initTRPC.meta<OpenApiMeta>().create();

Step 2: Use .meta() in your procedure

const router = t.router({
  myProcedure: t.procedure
    .meta({ openapi: { ignore: true } }) /* 👈 */
    .input(...
});

Comparison

trpc-openapi and its new fork trpc-to-openapi are the two relevant libraries.

They modify your API by adding new endpoints

These other libraries do not simply generate an OpenAPI spec for your existing tRPC server. They add new endpoints to your server and then generate an OpenAPI spec for those new endpoints.

For example:

// trpc-openapi example:

export const appRouter = t.router({
  sayHello: t.procedure

    // trpc-openapi adds a new endpoint to your server (`/say-hello`)
    // and the generated OpenAPI spec only includes this new `/say-hello`
    // endpoint, not the original `/trpc/sayHello` procedure
    .meta({ /* 👉 */ openapi: { method: "GET", path: "/say-hello" } }),
});

In comparison, trpc-openapi-2 simply generates an OpenAPI spec for your existing tRPC API, without modifying your API functionality at all.

They require you to use .meta() on every procedure

These libraries require that you add .meta() to every procedure that you want included in your OpenAPI spec. In comparison, with trpc-openapi-2 you can generate the full OpenAPI spec by calling trpcToOpenApi() without modifying your procedures at all.