wilddragon-site/node_modules/next/dist/docs/01-app/03-api-reference/01-directives/use-cache-private.md

---
title: 'use cache: private'
description: 'Learn how to use the "use cache: private" directive to cache functions that access runtime request APIs.'
version: experimental
related:
  title: Related
  description: View related API references.
  links:
    - app/api-reference/directives/use-cache
    - app/api-reference/config/next-config-js/cacheComponents
    - app/api-reference/functions/cacheLife
    - app/api-reference/functions/cacheTag
---

The `'use cache: private'` directive allows functions to access runtime request APIs like `cookies()`, `headers()`, and `searchParams` within a cached scope. However, results are **never stored on the server**, they're cached only in the browser's memory and do not persist across page reloads.

Reach for `'use cache: private'` when:

- You want to cache a function that already accesses runtime data, and refactoring to [move the runtime access outside and pass values as arguments](/docs/app/getting-started/caching#working-with-runtime-apis) is not practical.
- Compliance requirements prevent storing certain data on the server, even temporarily

Because this directive accesses runtime data, the function executes on every server render and is excluded from running during [static shell](/docs/app/getting-started/caching#how-rendering-works) generation.

It is **not** possible to configure custom cache handlers for `'use cache: private'`.

For a comparison of the different cache directives, see [How `use cache: remote` differs from `use cache` and `use cache: private`](/docs/app/api-reference/directives/use-cache-remote#how-use-cache-remote-differs-from-use-cache-and-use-cache-private).

> **Good to know**: This directive is marked as `experimental` because it depends on runtime prefetching, which is not yet stable. Runtime prefetching is an upcoming feature that will let the router prefetch past the [static shell](/docs/app/getting-started/caching#how-rendering-works) into **any** cached scope, not just private caches.

## Usage

To use `'use cache: private'`, enable the [`cacheComponents`](/docs/app/api-reference/config/next-config-js/cacheComponents) flag in your `next.config.ts` file:

```tsx filename="next.config.ts" switcher
import type { NextConfig } from 'next'

const nextConfig: NextConfig = {
  cacheComponents: true,
}

export default nextConfig
```

```jsx filename="next.config.js" switcher
/** @type {import('next').NextConfig} */
const nextConfig = {
  cacheComponents: true,
}

export default nextConfig
```

Then add `'use cache: private'` to your function along with a `cacheLife` configuration.

> **Good to know**: This directive is not available in Route Handlers.

### Basic example

In this example, we demonstrate that you can access cookies within a `'use cache: private'` scope:

```tsx filename="app/product/[id]/page.tsx" switcher
import { Suspense } from 'react'
import { cookies } from 'next/headers'
import { cacheLife, cacheTag } from 'next/cache'

export async function generateStaticParams() {
  return [{ id: '1' }]
}

export default async function ProductPage({
  params,
}: {
  params: Promise<{ id: string }>
}) {
  const { id } = await params

  return (
    <div>
      <ProductDetails id={id} />
      <Suspense fallback={<div>Loading recommendations...</div>}>
        <Recommendations productId={id} />
      </Suspense>
    </div>
  )
}

async function Recommendations({ productId }: { productId: string }) {
  const recommendations = await getRecommendations(productId)

  return (
    <div>
      {recommendations.map((rec) => (
        <ProductCard key={rec.id} product={rec} />
      ))}
    </div>
  )
}

async function getRecommendations(productId: string) {
  'use cache: private'
  cacheTag(`recommendations-${productId}`)
  cacheLife({ stale: 60 })

  // Access cookies within private cache functions
  const sessionId = (await cookies()).get('session-id')?.value || 'guest'

  return getPersonalizedRecommendations(productId, sessionId)
}
```

```jsx filename="app/product/[id]/page.js" switcher
import { Suspense } from 'react'
import { cookies } from 'next/headers'
import { cacheLife, cacheTag } from 'next/cache'

export async function generateStaticParams() {
  return [{ id: '1' }]
}

export default async function ProductPage({ params }) {
  const { id } = await params

  return (
    <div>
      <ProductDetails id={id} />
      <Suspense fallback={<div>Loading recommendations...</div>}>
        <Recommendations productId={id} />
      </Suspense>
    </div>
  )
}

async function Recommendations({ productId }) {
  const recommendations = await getRecommendations(productId)

  return (
    <div>
      {recommendations.map((rec) => (
        <ProductCard key={rec.id} product={rec} />
      ))}
    </div>
  )
}

async function getRecommendations(productId) {
  'use cache: private'
  cacheTag(`recommendations-${productId}`)
  cacheLife({ stale: 60 })

  // Access cookies within private cache functions
  const sessionId = (await cookies()).get('session-id')?.value || 'guest'

  return getPersonalizedRecommendations(productId, sessionId)
}
```

> **Good to know**: The `stale` time must be at least 30 seconds for runtime prefetching to work. See [`cacheLife` client cache behavior](/docs/app/api-reference/functions/cacheLife#client-cache-behavior) for details.

## Request APIs allowed in private caches

The following request-specific APIs can be used inside `'use cache: private'` functions:

| API            | Allowed in `use cache` | Allowed in `'use cache: private'` |
| -------------- | ---------------------- | --------------------------------- |
| `cookies()`    | No                     | Yes                               |
| `headers()`    | No                     | Yes                               |
| `searchParams` | No                     | Yes                               |
| `connection()` | No                     | No                                |

> **Note:** The [`connection()`](https://nextjs.org/docs/app/api-reference/functions/connection) API is prohibited in both `use cache` and `'use cache: private'` as it provides connection-specific information that cannot be safely cached.

## Version History

| Version   | Changes                                                              |
| --------- | -------------------------------------------------------------------- |
| `v16.0.0` | `"use cache: private"` is enabled with the Cache Components feature. |