Streaming & Suspense

Overview

Streaming lets the server send HTML in chunks so users see content before all data is ready. In the App Router you enable it with React <Suspense> boundaries or a loading.tsx file. Slow data fetches render a fallback first, then swap in the real content as it resolves, improving perceived performance.

Syntax / Usage

Wrap a slow async component in <Suspense> and provide a fallback. The rest of the page streams immediately.

// app/page.tsx
import { Suspense } from 'react'

export default function Page() {
  return (
    <main>
      <h1>Dashboard</h1>
      <Suspense fallback={<p>Loading revenue…</p>}>
        <Revenue />
      </Suspense>
    </main>
  )
}

async function Revenue() {
  const data = await getRevenue() // slow
  return <RevenueChart data={data} />
}

Examples

Use loading.tsx for instant route-level loading UI:

// app/dashboard/loading.tsx
export default function Loading() {
  return <DashboardSkeleton />
}

Stream multiple independent sections so each appears as soon as it is ready:

import { Suspense } from 'react'

export default function Page() {
  return (
    <>
      <Suspense fallback={<CardSkeleton />}>
        <LatestOrders />
      </Suspense>
      <Suspense fallback={<CardSkeleton />}>
        <TopCustomers />
      </Suspense>
    </>
  )
}

Common Mistakes

• Awaiting slow data in the page component itself, which blocks the whole route
• Wrapping the entire page in one boundary instead of isolating slow parts
• Forgetting a key or stable fallback, causing layout shift when content loads
• Expecting loading.tsx to apply to nested layouts it does not wrap
• Using Suspense for client-only fetching where it will not stream from the server

See Also

nextjs-data-fetching server-components app-router