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Sveltejs Academy · Lesson

End-to-End Type Safety with tRPC

Add tRPC to a SvelteKit project for fully typed client-server communication.

Lesson 4 of 413 steps

End-to-End Type Safety with tRPC is a free Sveltejs Academy lesson on CoddyKit. This is lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Sveltejs Academy learning path, and your progress syncs across the web and the CoddyKit app. The Sveltejs Academy course includes 4 lessons in total.

What tRPC Is

tRPC enables fully typed API calls without code generation: server types flow directly to clients.

Install

Add tRPC and a SvelteKit adapter.

npm install @trpc/server @trpc/client trpc-sveltekit

Define Routers

Procedures are typed functions grouped into routers.

export const appRouter = router({
  users: router({
    list: publicProcedure.query(() => db.select().from(users))
  })
});

SvelteKit Handler

Mount the router at /trpc/[...path]/+server.js.

Client Setup

Create a typed tRPC client that infers types from the router.

export const trpc = createTRPCSvelteClient<AppRouter>();

Type-Safe Calls

The client autocompletes procedures and infers argument and return types.

const users = await trpc.users.list.query();

Validation

Pair with Zod schemas for input validation and types in one place.

Mutations

Use publicProcedure.input(z.object({...})).mutation() for typed mutations.

Middleware

Add tRPC middleware for auth, logging, or rate limiting before procedures run.

SSR Friendly

tRPC works with SvelteKit's SSR via the trpc-sveltekit adapter.

Compared to REST/GraphQL

tRPC removes the schema layer; client and server share TypeScript types directly.

Quick Check

What is the main benefit of tRPC?

Answer it in the interactive lesson

Recap

tRPC gives end-to-end type-safe API calls in SvelteKit, removing the need for OpenAPI or GraphQL schemas.

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Frequently Asked Questions

Is the “End-to-End Type Safety with tRPC” lesson free?

Yes — the full text of “End-to-End Type Safety with tRPC” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Sveltejs Academy course, upgrade to CoddyKit PRO. The Sveltejs Academy course includes 4 lessons in total.

What will I learn in “End-to-End Type Safety with tRPC”?

Add tRPC to a SvelteKit project for fully typed client-server communication. You practise Sveltejs Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Sveltejs Academy?

No prior experience is required. Sveltejs Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 4 of 4.

How long does the “End-to-End Type Safety with tRPC” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Sveltejs Academy lesson?

Yes. Every Sveltejs Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. Auth + Database + API: Architecture
  2. Drizzle ORM with SvelteKit
  3. Deploying to Vercel with a Database
  4. End-to-End Type Safety with tRPC
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