Tanstack Start

TanStack Start Skills

Overview

TanStack Start is a full-stack React framework built on TanStack Router, powered by Vite and Nitro (via Vinxi). It provides server-side rendering, streaming, server functions (RPC), middleware, API routes, and deploys to any platform via Nitro presets.

Package: @tanstack/react-start Router Plugin: @tanstack/router-plugin Build Tool: Vinxi (Vite + Nitro) Status: RC (Release Candidate) RSC Support: React Server Components support is in active development and will land as a non-breaking v1.x addition

Installation & Project Setup

npx @tanstack/cli create my-app
# Or manually:
npm install @tanstack/react-start @tanstack/react-router react react-dom
npm install -D @tanstack/router-plugin typescript vite vite-tsconfig-paths

Project Structure

my-app/
  app/
    routes/
      __root.tsx          # Root layout
      index.tsx           # / route
      posts.$postId.tsx   # /posts/:postId
      api/
        users.ts          # /api/users API route
    client.tsx            # Client entry
    router.tsx            # Router creation
    ssr.tsx               # SSR entry
    routeTree.gen.ts      # Auto-generated route tree
  app.config.ts           # TanStack Start config
  tsconfig.json
  package.json

Configuration (app.config.ts)

import { defineConfig } from '@tanstack/react-start/config'
import viteTsConfigPaths from 'vite-tsconfig-paths'

export default defineConfig({
  vite: {
    plugins: [
      viteTsConfigPaths({ projects: ['./tsconfig.json'] }),
    ],
  },
  server: {
    preset: 'node-server', // 'vercel' | 'netlify' | 'cloudflare-pages' | etc.
  },
  tsr: {
    appDirectory: './app',
    routesDirectory: './app/routes',
    generatedRouteTree: './app/routeTree.gen.ts',
  },
})

Server Functions (createServerFn)

Server functions provide type-safe RPC calls between client and server.

Basic Server Functions

import { createServerFn } from '@tanstack/react-start'

// GET (data fetching, cacheable)
const getUsers = createServerFn()
  .handler(async () => {
    const users = await db.query.users.findMany()
    return users
  })

// POST (mutations, side effects)
const createUser = createServerFn({ method: 'POST' })
  .validator((data: { name: string; email: string }) => data)
  .handler(async ({ data }) => {
    const user = await db.insert(users).values(data).returning()
    return user
  })

With Zod Validation

import { z } from 'zod'

const updateUser = createServerFn({ method: 'POST' })
  .validator(
    z.object({
      id: z.string(),
      name: z.string().min(1),
      email: z.string().email(),
    })
  )
  .handler(async ({ data }) => {
    // data is fully typed: { id: string; name: string; email: string }
    return await db.update(users).set(data).where(eq(users.id, data.id))
  })

Middleware

Creating Middleware

import { createMiddleware } from '@tanstack/react-start'

const loggingMiddleware = createMiddleware().handler(async ({ next }) => {
  console.log('Request started')
  const result = await next()
  console.log('Request completed')
  return result
})

Auth Middleware with Context

const authMiddleware = createMiddleware().handler(async ({ next }) => {
  const request = getWebRequest()
  const session = await getSession(request)

  if (!session?.user) {
    throw redirect({ to: '/login' })
  }

  // Pass typed context to handler
  return next({ context: { user: session.user } })
})

Chaining Middleware

const adminMiddleware = createMiddleware()
  .middleware([authMiddleware])
  .handler(async ({ next, context }) => {
    // context.user is typed from authMiddleware
    if (context.user.role !== 'admin') {
      throw redirect({ to: '/unauthorized' })
    }
    return next({ context: { isAdmin: true } })
  })

// Usage
const adminAction = createServerFn({ method: 'POST' })
  .middleware([adminMiddleware])
  .handler(async ({ context }) => {
    // context: { user: User; isAdmin: boolean }
    return { success: true }
  })

API Routes (Server Routes)

// app/routes/api/users.ts
import { createAPIFileRoute } from '@tanstack/react-start/api'

export const APIRoute = createAPIFileRoute('/api/users')({
  GET: async ({ request }) => {
    const users = await db.query.users.findMany()
    return Response.json(users)
  },
  POST: async ({ request }) => {
    const body = await request.json()
    const user = await db.insert(users).values(body).returning()
    return new Response(JSON.stringify(user), { status: 201 })
  },
})

SSR Strategies

Streaming SSR (Default)

export const Route = createFileRoute('/dashboard')({
  loader: async () => ({
    criticalData: await fetchCriticalData(),
    deferredData: defer(fetchSlowData()),
  }),
  component: Dashboard,
})

function Dashboard() {
  const { criticalData, deferredData } = Route.useLoaderData()
  return (
    <div>
      <CriticalSection data={criticalData} />
      <Suspense fallback={<Loading />}>
        <Await promise={deferredData}>
          {(data) => <SlowSection data={data} />}
        </Await>
      </Suspense>
    </div>
  )
}

Deployment

Supported Platforms (Nitro Presets)

// app.config.ts
export default defineConfig({
  server: {
    preset: 'node-server',        // Self-hosted Node.js
    // preset: 'vercel',          // Vercel
    // preset: 'netlify',         // Netlify
    // preset: 'cloudflare-pages', // Cloudflare Pages
    // preset: 'aws-lambda',      // AWS Lambda
    // preset: 'deno-server',     // Deno Deploy
    // preset: 'bun',             // Bun
  },
})

Best Practices

1. Use validators for all server function inputs - runtime safety and TypeScript inference
2. Compose middleware for cross-cutting concerns (auth, logging, rate limiting)
3. Use createServerFn GET for data fetching (cacheable, preloadable)
4. Use createServerFn POST for mutations and side effects
5. Use beforeLoad for route-level auth guards
6. Use defer() for non-critical data to improve TTFB
7. Set defaultPreload: 'intent' on the router for instant navigation
8. Co-locate server functions with the routes that use them

Common Pitfalls

• Server functions cannot close over client-side variables (they're extracted to separate bundles)
• Data returned from server functions must be serializable
• Forgetting await in loaders leads to streaming issues
• Importing server-only code in client bundles causes build errors
• Missing declare module '@tanstack/react-router' loses all type safety

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