--- title: Functions description: API Reference for Next.js Functions and Hooks. url: "https://nextjs.org/docs/app/api-reference/functions" docs_index: /docs/llms.txt lastUpdated: 2025-06-16 prerequisites: - "API Reference: /docs/app/api-reference" --- > For an index of all documentation, see [/docs/llms.txt](/docs/llms.txt). - [after](/docs/app/api-reference/functions/after): API Reference for the after function. - [cacheLife](/docs/app/api-reference/functions/cacheLife): Learn how to use the cacheLife function to set the cache expiration time for a cached function or component. - [cacheTag](/docs/app/api-reference/functions/cacheTag): Learn how to use the cacheTag function to manage cache invalidation in your Next.js application. - [catchError](/docs/app/api-reference/functions/catchError): API Reference for the catchError function. - [connection](/docs/app/api-reference/functions/connection): API Reference for the connection function. - [cookies](/docs/app/api-reference/functions/cookies): API Reference for the cookies function. - [draftMode](/docs/app/api-reference/functions/draft-mode): API Reference for the draftMode function. - [fetch](/docs/app/api-reference/functions/fetch): API reference for the extended fetch function. - [forbidden](/docs/app/api-reference/functions/forbidden): API Reference for the forbidden function. - [generateImageMetadata](/docs/app/api-reference/functions/generate-image-metadata): Learn how to generate multiple images in a single Metadata API special file. - [generateMetadata](/docs/app/api-reference/functions/generate-metadata): Learn how to add Metadata to your Next.js application for improved search engine optimization (SEO) and web shareability. - [generateSitemaps](/docs/app/api-reference/functions/generate-sitemaps): Learn how to use the generateSitemaps function to create multiple sitemaps for your application. - [generateStaticParams](/docs/app/api-reference/functions/generate-static-params): API reference for the generateStaticParams function. - [generateViewport](/docs/app/api-reference/functions/generate-viewport): API Reference for the generateViewport function. - [headers](/docs/app/api-reference/functions/headers): API reference for the headers function. - [ImageResponse](/docs/app/api-reference/functions/image-response): API Reference for the ImageResponse constructor. - [io](/docs/app/api-reference/functions/io): API Reference for the io function. - [navigation](/docs/app/api-reference/functions/navigation): Defer runtime work until the user navigates with the navigation function. - [NextRequest](/docs/app/api-reference/functions/next-request): API Reference for NextRequest. - [NextResponse](/docs/app/api-reference/functions/next-response): API Reference for NextResponse. - [root-params](/docs/app/api-reference/functions/next-root-params): API Reference for the next/root-params module that provides access to root-level route parameters. - [notFound](/docs/app/api-reference/functions/not-found): API Reference for the notFound function. - [permanentRedirect](/docs/app/api-reference/functions/permanentRedirect): API Reference for the permanentRedirect function. - [prefetch](/docs/app/api-reference/functions/prefetch): Defer runtime work until a per-link prefetch or navigation with the prefetch function. - [redirect](/docs/app/api-reference/functions/redirect): API Reference for the redirect function. - [refresh](/docs/app/api-reference/functions/refresh): API Reference for the refresh function. - [revalidatePath](/docs/app/api-reference/functions/revalidatePath): API Reference for the revalidatePath function. - [revalidateTag](/docs/app/api-reference/functions/revalidateTag): API Reference for the revalidateTag function. - [unauthorized](/docs/app/api-reference/functions/unauthorized): API Reference for the unauthorized function. - [unstable\_cache](/docs/app/api-reference/functions/unstable_cache): API Reference for the unstable\_cache function. - [unstable\_noStore](/docs/app/api-reference/functions/unstable_noStore): API Reference for the unstable\_noStore function. - [unstable\_rethrow](/docs/app/api-reference/functions/unstable_rethrow): API Reference for the unstable\_rethrow function. - [updateTag](/docs/app/api-reference/functions/updateTag): API Reference for the updateTag function. - [useLinkStatus](/docs/app/api-reference/functions/use-link-status): API Reference for the useLinkStatus hook. - [useOffline](/docs/app/api-reference/functions/use-offline): API Reference for the useOffline hook. - [useParams](/docs/app/api-reference/functions/use-params): API Reference for the useParams hook. - [usePathname](/docs/app/api-reference/functions/use-pathname): API Reference for the usePathname hook. - [useReportWebVitals](/docs/app/api-reference/functions/use-report-web-vitals): API Reference for the useReportWebVitals function. - [useRouter](/docs/app/api-reference/functions/use-router): API reference for the useRouter hook. - [useSearchParams](/docs/app/api-reference/functions/use-search-params): API Reference for the useSearchParams hook. - [useSelectedLayoutSegment](/docs/app/api-reference/functions/use-selected-layout-segment): API Reference for the useSelectedLayoutSegment hook. - [useSelectedLayoutSegments](/docs/app/api-reference/functions/use-selected-layout-segments): API Reference for the useSelectedLayoutSegments hook. - [userAgent](/docs/app/api-reference/functions/userAgent): The userAgent helper extends the Web Request API with additional properties and methods to interact with the user agent object from the request. --- For a semantic overview of all documentation, see [/sitemap.md](/sitemap.md) For an index of all available documentation, see [/docs/llms.txt](/docs/llms.txt)