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---
title: getStaticPaths
description: Fetch data and generate static pages with `getStaticPaths`. Learn more about this API for data fetching in Next.js.
---
If a page has [Dynamic Routes](/docs/pages/building-your-application/routing/dynamic-routes) and uses `getStaticProps`, it needs to define a list of paths to be statically generated.
When you export a function called `getStaticPaths` (Static Site Generation) from a page that uses dynamic routes, Next.js will statically pre-render all the paths specified by `getStaticPaths`.
```tsx filename="pages/repo/[name].tsx" switcher
import type {
InferGetStaticPropsType,
GetStaticProps,
GetStaticPaths,
} from 'next'
type Repo = {
name: string
stargazers_count: number
}
export const getStaticPaths = (async () => {
return {
paths: [
{
params: {
name: 'next.js',
},
}, // See the "paths" section below
],
fallback: true, // false or "blocking"
}
}) satisfies GetStaticPaths
export const getStaticProps = (async (context) => {
const res = await fetch('https://api.github.com/repos/vercel/next.js')
const repo = await res.json()
return { props: { repo } }
}) satisfies GetStaticProps<{
repo: Repo
}>
export default function Page({
repo,
}: InferGetStaticPropsType<typeof getStaticProps>) {
return repo.stargazers_count
}
```
```jsx filename="pages/repo/[name].js" switcher
export async function getStaticPaths() {
return {
paths: [
{
params: {
name: 'next.js',
},
}, // See the "paths" section below
],
fallback: true, // false or "blocking"
}
}
export async function getStaticProps() {
const res = await fetch('https://api.github.com/repos/vercel/next.js')
const repo = await res.json()
return { props: { repo } }
}
export default function Page({ repo }) {
return repo.stargazers_count
}
```
The [`getStaticPaths` API reference](/docs/pages/api-reference/functions/get-static-paths) covers all parameters and props that can be used with `getStaticPaths`.
## When should I use getStaticPaths?
You should use `getStaticPaths` if you’re statically pre-rendering pages that use dynamic routes and:
- The data comes from a headless CMS
- The data comes from a database
- The data comes from the filesystem
- The data can be publicly cached (not user-specific)
- The page must be pre-rendered (for SEO) and be very fast — `getStaticProps` generates `HTML` and `JSON` files, both of which can be cached by a CDN for performance
## When does getStaticPaths run
`getStaticPaths` will only run during build in production, it will not be called during runtime. You can validate code written inside `getStaticPaths` is removed from the client-side bundle [with this tool](https://next-code-elimination.vercel.app/).
### How does getStaticProps run with regards to getStaticPaths
- `getStaticProps` runs during `next build` for any `paths` returned during build
- `getStaticProps` runs in the background when using `fallback: true`
- `getStaticProps` is called before initial render when using `fallback: blocking`
## Where can I use getStaticPaths
- `getStaticPaths` **must** be used with `getStaticProps`
- You **cannot** use `getStaticPaths` with [`getServerSideProps`](/docs/pages/building-your-application/data-fetching/get-server-side-props)
- You can export `getStaticPaths` from a [Dynamic Route](/docs/pages/building-your-application/routing/dynamic-routes) that also uses `getStaticProps`
- You **cannot** export `getStaticPaths` from non-page file (e.g. your `components` folder)
- You must export `getStaticPaths` as a standalone function, and not a property of the page component
## Runs on every request in development
In development (`next dev`), `getStaticPaths` will be called on every request.
## Generating paths on-demand
`getStaticPaths` allows you to control which pages are generated during the build instead of on-demand with [`fallback`](/docs/pages/api-reference/functions/get-static-paths#fallback-blocking). Generating more pages during a build will cause slower builds.
You can defer generating all pages on-demand by returning an empty array for `paths`. This can be especially helpful when deploying your Next.js application to multiple environments. For example, you can have faster builds by generating all pages on-demand for previews (but not production builds). This is helpful for sites with hundreds/thousands of static pages.
```jsx filename="pages/posts/[id].js"
export async function getStaticPaths() {
// When this is true (in preview environments) don't
// prerender any static pages
// (faster builds, but slower initial page load)
if (process.env.SKIP_BUILD_STATIC_GENERATION) {
return {
paths: [],
fallback: 'blocking',
}
}
// 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 prerender based on posts
// In production environments, prerender all pages
// (slower builds, but faster initial page load)
const paths = posts.map((post) => ({
params: { id: post.id },
}))
// { fallback: false } means other routes should 404
return { paths, fallback: false }
}
```
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