next.js/docs/02-pages/03-building-your-application/02-rendering/02-static-site-generation.mdx

---
title: Static Site Generation (SSG)
description: Use Static Site Generation (SSG) to pre-render pages at build time.
---

<details>
  <summary>Examples</summary>

- [Agility CMS Example](https://github.com/vercel/next.js/tree/canary/examples/cms-agilitycms) ([Demo](https://next-blog-agilitycms.vercel.app/))
- [Builder.io Example](https://github.com/vercel/next.js/tree/canary/examples/cms-builder-io) ([Demo](https://cms-builder-io.vercel.app/))
- [ButterCMS Example](https://github.com/vercel/next.js/tree/canary/examples/cms-buttercms) ([Demo](https://next-blog-buttercms.vercel.app/))
- [Contentful Example](https://github.com/vercel/next.js/tree/canary/examples/cms-contentful) ([Demo](https://app-router-contentful.vercel.app/))
- [Cosmic Example](https://github.com/vercel/next.js/tree/canary/examples/cms-cosmic) ([Demo](https://next-blog-cosmic.vercel.app/))
- [DatoCMS Example](https://github.com/vercel/next.js/tree/canary/examples/cms-datocms) ([Demo](https://next-blog-datocms.vercel.app/))
- [DotCMS Example](https://github.com/vercel/next.js/tree/canary/examples/cms-dotcms) ([Demo](https://nextjs-dotcms-blog.vercel.app/))
- [Drupal Example](https://github.com/vercel/next.js/tree/canary/examples/cms-drupal) ([Demo](https://cms-drupal.vercel.app/))
- [Enterspeed Example](https://github.com/vercel/next.js/tree/canary/examples/cms-enterspeed) ([Demo](https://next-blog-demo.enterspeed.com/))
- [GraphCMS Example](https://github.com/vercel/next.js/tree/canary/examples/cms-graphcms) ([Demo](https://next-blog-graphcms.vercel.app/))
- [Keystone Example](https://github.com/vercel/next.js/tree/canary/examples/cms-keystonejs-embedded) ([Demo](https://nextjs-keystone-demo.vercel.app/))
- [Kontent.ai Example](https://github.com/vercel/next.js/tree/canary/examples/cms-kontent-ai) ([Demo](https://next-blog-kontent-ai.vercel.app/))
- [Makeswift Example](https://github.com/vercel/next.js/tree/canary/examples/cms-makeswift) ([Demo](https://nextjs-makeswift-example.vercel.app/))
- [Plasmic Example](https://github.com/vercel/next.js/tree/canary/examples/cms-plasmic) ([Demo](https://nextjs-plasmic-example.vercel.app/))
- [Prepr Example](https://github.com/vercel/next.js/tree/canary/examples/cms-prepr) ([Demo](https://next-blog-prepr.vercel.app/))
- [Prismic Example](https://github.com/vercel/next.js/tree/canary/examples/cms-prismic) ([Demo](https://next-blog-prismic.vercel.app/))
- [Sanity Example](https://github.com/vercel/next.js/tree/canary/examples/cms-sanity) ([Demo](https://next-blog.sanity.build/))
- [Sitecore XM Cloud Example](https://github.com/vercel/next.js/tree/canary/examples/cms-sitecore-xmcloud) ([Demo](https://vercel-sitecore-xmcloud-demo.vercel.app/))
- [Storyblok Example](https://github.com/vercel/next.js/tree/canary/examples/cms-storyblok) ([Demo](https://next-blog-storyblok.vercel.app/))
- [Strapi Example](https://github.com/vercel/next.js/tree/canary/examples/cms-strapi) ([Demo](https://next-blog-strapi.vercel.app/))
- [TakeShape Example](https://github.com/vercel/next.js/tree/canary/examples/cms-takeshape) ([Demo](https://next-blog-takeshape.vercel.app/))
- [Tina Example](https://github.com/vercel/next.js/tree/canary/examples/cms-tina) ([Demo](https://cms-tina-example.vercel.app/))
- [Umbraco Example](https://github.com/vercel/next.js/tree/canary/examples/cms-umbraco) ([Demo](https://nextjs-umbraco-sample-blog.vercel.app/))
- [Umbraco Heartcore Example](https://github.com/vercel/next.js/tree/canary/examples/cms-umbraco-heartcore) ([Demo](https://next-blog-umbraco-heartcore.vercel.app/))
- [Webiny Example](https://github.com/vercel/next.js/tree/canary/examples/cms-webiny) ([Demo](https://webiny-headlesscms-nextjs-example.vercel.app/))
- [WordPress Example](https://github.com/vercel/next.js/tree/canary/examples/cms-wordpress) ([Demo](https://next-blog-wordpress.vercel.app/))
- [Blog Starter Example](https://github.com/vercel/next.js/tree/canary/examples/blog-starter) ([Demo](https://next-blog-starter.vercel.app/))
- [Static Tweet (Demo)](https://react-tweet.vercel.app/)

</details>

If a page uses **Static Generation**, the page HTML is generated at **build time**. That means in production, the page HTML is generated when you run `next build`. This HTML will then be reused on each request. It can be cached by a CDN.

In Next.js, you can statically generate pages **with or without data**. Let's take a look at each case.

### Static Generation without data

By default, Next.js pre-renders pages using Static Generation without fetching data. Here's an example:

```jsx
function About() {
  return <div>About</div>
}

export default About
```

Note that this page does not need to fetch any external data to be pre-rendered. In cases like this, Next.js generates a single HTML file per page during build time.

### Static Generation with data

Some pages require fetching external data for pre-rendering. There are two scenarios, and one or both might apply. In each case, you can use these functions that Next.js provides:

1. Your page **content** depends on external data: Use `getStaticProps`.
2. Your page **paths** depend on external data: Use `getStaticPaths` (usually in addition to `getStaticProps`).

#### Scenario 1: Your page content depends on external data

**Example**: Your blog page might need to fetch the list of blog posts from a CMS (content management system).

```jsx
// TODO: Need to fetch `posts` (by calling some API endpoint)
//       before this page can be pre-rendered.
export default function Blog({ posts }) {
  return (
    <ul>
      {posts.map((post) => (
        <li>{post.title}</li>
      ))}
    </ul>
  )
}
```

To fetch this data on pre-render, Next.js allows you to `export` an `async` function called `getStaticProps` from the same file. This function gets called at build time and lets you pass fetched data to the page's `props` on pre-render.

```jsx
export default function Blog({ posts }) {
  // Render posts...
}

// This function gets called at build time
export async function getStaticProps() {
  // Call an external API endpoint to get posts
  const res = await fetch('https://.../posts')
  const posts = await res.json()

  // By returning { props: { posts } }, the Blog component
  // will receive `posts` as a prop at build time
  return {
    props: {
      posts,
    },
  }
}
```

To learn more about how `getStaticProps` works, check out the [Data Fetching documentation](/docs/pages/building-your-application/data-fetching/get-static-props).

#### Scenario 2: Your page paths depend on external data

Next.js allows you to create pages with **dynamic routes**. For example, you can create a file called `pages/posts/[id].js` to show a single blog post based on `id`. This will allow you to show a blog post with `id: 1` when you access `posts/1`.

> To learn more about dynamic routing, check the [Dynamic Routing documentation](/docs/pages/building-your-application/routing/dynamic-routes).

However, which `id` you want to pre-render at build time might depend on external data.

**Example**: suppose that you've only added one blog post (with `id: 1`) to the database. In this case, you'd only want to pre-render `posts/1` at build time.

Later, you might add the second post with `id: 2`. Then you'd want to pre-render `posts/2` as well.

So your page **paths** that are pre-rendered depend on external data. To handle this, Next.js lets you `export` an `async` function called `getStaticPaths` from a dynamic page (`pages/posts/[id].js` in this case). This function gets called at build time and lets you specify which paths you want to pre-render.

```jsx
// This function gets called at build time
export async function getStaticPaths() {
  // Call an external API endpoint to get posts
  const res = await fetch('https://.../posts')
  const posts = await res.json()

  // Get the paths we want to pre-render based on posts
  const paths = posts.map((post) => ({
    params: { id: post.id },
  }))

  // We'll pre-render only these paths at build time.
  // { fallback: false } means other routes should 404.
  return { paths, fallback: false }
}
```

Also in `pages/posts/[id].js`, you need to export `getStaticProps` so that you can fetch the data about the post with this `id` and use it to pre-render the page:

```jsx
export default function Post({ post }) {
  // Render post...
}

export async function getStaticPaths() {
  // ...
}

// This also gets called at build time
export async function getStaticProps({ params }) {
  // params contains the post `id`.
  // If the route is like /posts/1, then params.id is 1
  const res = await fetch(`https://.../posts/${params.id}`)
  const post = await res.json()

  // Pass post data to the page via props
  return { props: { post } }
}
```

To learn more about how `getStaticPaths` works, check out the [Data Fetching documentation](/docs/pages/building-your-application/data-fetching/get-static-paths).

### When should I use Static Generation?

We recommend using **Static Generation** (with and without data) whenever possible because your page can be built once and served by CDN, which makes it much faster than having a server render the page on every request.

You can use Static Generation for many types of pages, including:

- Marketing pages
- Blog posts and portfolios
- E-commerce product listings
- Help and documentation

You should ask yourself: "Can I pre-render this page **ahead** of a user's request?" If the answer is yes, then you should choose Static Generation.

On the other hand, Static Generation is **not** a good idea if you cannot pre-render a page ahead of a user's request. Maybe your page shows frequently updated data, and the page content changes on every request.

In cases like this, you can do one of the following:

- Use Static Generation with **Client-side data fetching:** You can skip pre-rendering some parts of a page and then use client-side JavaScript to populate them. To learn more about this approach, check out the [Data Fetching documentation](/docs/pages/building-your-application/data-fetching/client-side).
- Use **Server-Side Rendering:** Next.js pre-renders a page on each request. It will be slower because the page cannot be cached by a CDN, but the pre-rendered page will always be up-to-date. We'll talk about this approach below.