# Source: https://nextjs.org/docs/pages/api-reference/functions/get-server-side-props.md

# Source: https://nextjs.org/docs/pages/building-your-application/data-fetching/get-server-side-props.md

# Source: https://nextjs.org/docs/pages/api-reference/functions/get-server-side-props.md

# Source: https://nextjs.org/docs/pages/building-your-application/data-fetching/get-server-side-props.md

# Source: https://nextjs.org/docs/pages/api-reference/functions/get-server-side-props.md

# Source: https://nextjs.org/docs/pages/building-your-application/data-fetching/get-server-side-props.md

# Source: https://nextjs.org/docs/pages/api-reference/functions/get-server-side-props.md

# Source: https://nextjs.org/docs/pages/building-your-application/data-fetching/get-server-side-props.md

# Source: https://nextjs.org/docs/pages/api-reference/functions/get-server-side-props.md

# Source: https://nextjs.org/docs/pages/building-your-application/data-fetching/get-server-side-props.md

# getServerSideProps


`getServerSideProps` is a Next.js function that can be used to fetch data and render the contents of a page at request time.

## Example

You can use `getServerSideProps` by exporting it from a Page Component. The example below shows how you can fetch data from a 3rd party API in `getServerSideProps`, and pass the data to the page as props:

```tsx filename="pages/index.tsx" switcher
import type { InferGetServerSidePropsType, GetServerSideProps } from 'next'

type Repo = {
  name: string
  stargazers_count: number
}

export const getServerSideProps = (async () => {
  // Fetch data from external API
  const res = await fetch('https://api.github.com/repos/vercel/next.js')
  const repo: Repo = await res.json()
  // Pass data to the page via props
  return { props: { repo } }
}) satisfies GetServerSideProps<{ repo: Repo }>

export default function Page({
  repo,
}: InferGetServerSidePropsType<typeof getServerSideProps>) {
  return (
    <main>
      <p>{repo.stargazers_count}</p>
    </main>
  )
}
```

```jsx filename="pages/index.js" switcher
export async function getServerSideProps() {
  // Fetch data from external API
  const res = await fetch('https://api.github.com/repos/vercel/next.js')
  const repo = await res.json()
  // Pass data to the page via props
  return { props: { repo } }
}

export default function Page({ repo }) {
  return (
    <main>
      <p>{repo.stargazers_count}</p>
    </main>
  )
}
```

## When should I use `getServerSideProps`?

You should use `getServerSideProps` if you need to render a page that relies on personalized user data, or information that can only be known at request time. For example, `authorization` headers or a geolocation.

If you do not need to fetch the data at request time, or would prefer to cache the data and pre-rendered HTML, we recommend using [`getStaticProps`](/docs/pages/building-your-application/data-fetching/get-static-props.md).

## Behavior

* `getServerSideProps` runs on the server.
* `getServerSideProps` can only be exported from a **page**.
* `getServerSideProps` returns JSON.
* When a user visits a page, `getServerSideProps` will be used to fetch data at request time, and the data is used to render the initial HTML of the page.
* `props` passed to the page component can be viewed on the client as part of the initial HTML. This is to allow the page to be [hydrated](https://react.dev/reference/react-dom/hydrate) correctly. Make sure that you don't pass any sensitive information that shouldn't be available on the client in `props`.
* When a user visits the page through [`next/link`](/docs/pages/api-reference/components/link.md) or [`next/router`](/docs/pages/api-reference/functions/use-router.md), Next.js sends an API request to the server, which runs `getServerSideProps`.
* You do not have to call a Next.js [API Route](/docs/pages/building-your-application/routing/api-routes.md) to fetch data when using `getServerSideProps` since the function runs on the server. Instead, you can call a CMS, database, or other third-party APIs directly from inside `getServerSideProps`.

> **Good to know:**
>
> * See [`getServerSideProps` API reference](/docs/pages/api-reference/functions/get-server-side-props.md) for parameters and props that can be used with `getServerSideProps`.
> * You can use the [next-code-elimination tool](https://next-code-elimination.vercel.app/) to verify what Next.js eliminates from the client-side bundle.

## Error Handling

If an error is thrown inside `getServerSideProps`, it will show the `pages/500.js` file. Check out the documentation for [500 page](/docs/pages/building-your-application/routing/custom-error.md#500-page) to learn more on how to create it. During development, this file will not be used and the development error overlay will be shown instead.

## Edge Cases

### Caching with Server-Side Rendering (SSR)

You can use caching headers (`Cache-Control`) inside `getServerSideProps` to cache dynamic responses. For example, using [`stale-while-revalidate`](https://web.dev/stale-while-revalidate/).

```jsx
// This value is considered fresh for ten seconds (s-maxage=10).
// If a request is repeated within the next 10 seconds, the previously
// cached value will still be fresh. If the request is repeated before 59 seconds,
// the cached value will be stale but still render (stale-while-revalidate=59).
//
// In the background, a revalidation request will be made to populate the cache
// with a fresh value. If you refresh the page, you will see the new value.
export async function getServerSideProps({ req, res }) {
  res.setHeader(
    'Cache-Control',
    'public, s-maxage=10, stale-while-revalidate=59'
  )

  return {
    props: {},
  }
}
```

However, before reaching for `cache-control`, we recommend seeing if [`getStaticProps`](/docs/pages/building-your-application/data-fetching/get-static-props.md) with [ISR](/docs/pages/guides/incremental-static-regeneration.md) is a better fit for your use case.