Does Fastify Work With tRPC?

Fully CompatibleLast verified: 2026-02-26

Fastify and tRPC work together seamlessly, with tRPC providing an official Fastify adapter for typesafe RPC endpoints.

Quick Facts

Compatibility

full

Setup Difficulty

Easy

Official Integration

Yes ✓

Confidence

high

Minimum Versions

Fastify: 3.0.0

tRPC: 9.0.0

How Fastify Works With tRPC

Fastify and tRPC integrate through tRPC's official `@trpc/server` adapter for Fastify, which handles HTTP request routing and response serialization. You define your tRPC router with procedures (queries, mutations, subscriptions) and mount it as a Fastify plugin using `fastifyTrpcPlugin`. The developer experience is excellent: you get end-to-end TypeScript type safety from client to server without code generation, while Fastify handles the HTTP layer with its characteristic performance and plugin ecosystem. The setup involves creating a tRPC router, wrapping it in Fastify using the adapter, and optionally configuring CORS, error handling, and middleware. Fastify's async-first design pairs naturally with tRPC's async procedure handlers. You can leverage Fastify's full plugin system for middleware, authentication, and other concerns while keeping your RPC logic cleanly separated in tRPC procedures. WebSocket support for real-time subscriptions works through Fastify's WebSocket plugin integration.

Best Use Cases

→Building full-stack Next.js or SvelteKit applications with a shared Fastify backend that doesn't require Next.js or SvelteKit's HTTP layer

→Creating microservices with typesafe internal APIs where multiple Fastify services communicate via tRPC clients

→Building real-time collaborative applications combining tRPC subscriptions with Fastify's performance for high-concurrency scenarios

→Migrating from traditional REST APIs to typesafe RPC while maintaining Fastify's plugin architecture and ecosystem

Quick Setup

bash

npm install fastify @trpc/server @trpc/client zod

typescript

import Fastify from 'fastify';
import { initTRPC } from '@trpc/server';
import { fastifyTRPCPlugin } from '@trpc/server/adapters/fastify';
import { z } from 'zod';

const t = initTRPC.create();

const appRouter = t.router({
  hello: t.procedure
    .input(z.object({ name: z.string() }))
    .query(({ input }) => `Hello, ${input.name}!`),
});

const fastify = Fastify();

await fastify.register(fastifyTRPCPlugin, {
  prefix: '/trpc',
  router: appRouter,
});

await fastify.listen({ port: 3000 });

export type AppRouter = typeof appRouter;

Known Issues & Gotchas

warning

Context initialization timing with async dependencies

Fix: Use tRPC's createContext with async operations; Fastify plugins load in order, so ensure auth/DB connections initialize before tRPC plugin

info

WebSocket subscriptions require additional Fastify WebSocket plugin configuration

Fix: Install @fastify/websocket separately and configure it before mounting tRPC adapter; check tRPC docs for ws transport setup

warning

Error serialization differences between tRPC and Fastify error handlers

Fix: Define custom error formatting in tRPC's error handler option to ensure consistent error responses across your API

Alternatives

•Express.js with tRPC - more ecosystem libraries but slower than Fastify
•Hono with tRPC - lightweight alternative with similar performance, better for edge/Cloudflare Workers
•Nitro (Nuxt server engine) with tRPC - opinionated Vue.js fullstack solution

Resources

docstRPC Fastify Adapter Documentation docsFastify Official Documentation tutorialtRPC Getting Started Guide githubtRPC Server GitHub Repository

Related Compatibility Guides

NestJS + tRPC Fastify + PostgreSQL Fastify + UploadThing Fastify + Paddle Fastify + Prisma Fastify + Drizzle ORM

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