trpc-panel

tRPC.panel()

Probably the easiest and cheapest way to build a testing UI and documentation for your tRPC endpoints. tRPC panel automatically generates a UI for manually testing your tRPC backend with 0 overhead:

trpc panel moves as fast as your trpc backend with minimal effort.

Check out our test app

Features

• Automatically inspect your tRPC router and recursively generate a typesafe UI
• Zero overhead
• No output schemas (procedure return types can be inferred as nature intended)
• New procedures will be added to your UI as you create them in your backend
• No compilation required, works with any backend
• Document your procedures and input parameters with minimal effort
• Supports nested routers, and nested input objects. The structure of the UI maps one-to-one to your API's routers and procedures.
• SideNav and VSCode-like procedure / router search to quickly find what you're looking for
• ✨ Transform data with built in superjson support.

Quick Start

Install with your preferred package manager:

yarn add trpc-panel

render your panel and return it from your backend (express example):

import { renderTrpcPanel } from "trpc-panel";
// ...
app.use("/panel", (_, res) => {
  return res.send(
    renderTrpcPanel(myTrpcRouter, { url: "http://localhost:4000/trpc" })
  );
});

trpc-panel just renders as a string, so it can be used with any backend.

NextJS / create-t3-app example

In Nextjs you'd want to create an api route somewhere like src/pages/api/panel.ts and send a text response:

import type { NextApiRequest, NextApiResponse } from "next";
import { renderTrpcPanel } from "trpc-panel";
import { appRouter } from "../../server/api/root";

export default async function handler(_: NextApiRequest, res: NextApiResponse) {
  res.status(200).send(
    renderTrpcPanel(appRouter, {
      url: "http://localhost:3000/api/trpc",
      transformer: "superjson",
    })
  );
}

Then we can visit the url http://localhost:3000/api/panel to use the panel. Here we do transformer: "superjson" assuming we have superjson set as the transformer in tRPC (which create-t3-app does by default).

Documenting Procedures

As of v1.1.0, trpc-panel supports documenting procedures.

Documentation is opt-in, meaning you only need to set it up if you want to use it. When docs are included for your trpc procedure, a "Docs" section will appear in your procedure:

Procedure Descriptions

trpc-panel supports documenting procedures via trpc meta. First setup your trpc instance to be typed with TRPCPanelMeta:

import { initTRPC } from "@trpc/server";
import { TRPCPanelMeta } from "trpc-panel";

const t = initTRPC.meta().create();

Then in your routers you can provide a description to the meta:

export const appRouter = t.router({
  sayHello: t.procedure
    .meta({ /*  */ description: "This shows in the panel." })
    .input(z.object({ name: z.string() }))
    .query(({ input }) => {
      return { greeting: `Hello ${input.name}!` };
    });
});

Input Parameter Descriptions

trpc-panel supports documenting parameters via zod's .describe() method. This allows developers to quickly write documentation as they're writing schemas:

export const appRouter = t.router({
  sayHello: t.procedure
    .input(z.object({
        name: z.string().describe("The name to say hello too.")
    }))
    .query(({ input }) => {
      return { greeting: `Hello ${input.name}!` };
    });
});

Whatever you pass to describe() will appear in the docs section. Any input fields without a description will not appear in the docs section.

Data Transformers

Trpc panel supports superjson, just pass it into the transformer option:

app.use("/panel", (_, res) => {
  return res.send(
    renderTrpcPanel(myTrpcRouter, {
      url: "http://localhost:4000/trpc",
      transformer: "superjson",
    })
  );
});

Contributing

trpc-panel welcomes and encourages open source contributions. Please see our contributing guide for information on how to develop locally.

Limitations

Currently, tRPC panel only supports tRPC v10 and only works with zod input schemas. With it's current design it would be feasible to easily add support for other input types as well

There are no plans to support v9 or other previous tRPC versions.

Supported zod types

The following are supported

• Array
• BigInt
• Boolean
• Branded
• Default
• DiscriminatedUnion
• Effects
• Enum
• Literal
• Nullable
• Null
• Nullish
• Number
• Object
• Optional
• Promise
• String
• Undefined

We would like to add the following types:

• Union
• Tuple
• Record
• Never
• Map (superjson only)
• Set (superjson only)
• Date (superjson only)
• Any