# Source: https://nextjs.org/docs/app/getting-started/metadata-and-og-images.md

# Metadata and OG images
@doc-version: 16.0.4


The Metadata APIs can be used to define your application metadata for improved SEO and web shareability and include:

1. [The static `metadata` object](#static-metadata)
2. [The dynamic `generateMetadata` function](#generated-metadata)
3. Special [file conventions](/docs/app/api-reference/file-conventions/metadata.md) that can be used to add static or dynamically generated [favicons](#favicons) and [OG images](#static-open-graph-images).

With all the options above, Next.js will automatically generate the relevant `<head>` tags for your page, which can be inspected in the browser's developer tools.

The `metadata` object and `generateMetadata` function exports are only supported in Server Components.

## Default fields

There are two default `meta` tags that are always added even if a route doesn't define metadata:

* The [meta charset tag](https://developer.mozilla.org/docs/Web/HTML/Element/meta#attr-charset) sets the character encoding for the website.
* The [meta viewport tag](https://developer.mozilla.org/docs/Web/HTML/Viewport_meta_tag) sets the viewport width and scale for the website to adjust for different devices.

```html
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
```

The other metadata fields can be defined with the `Metadata` object (for [static metadata](#static-metadata)) or the `generateMetadata` function (for [generated metadata](#generated-metadata)).

## Static metadata

To define static metadata, export a [`Metadata` object](/docs/app/api-reference/functions/generate-metadata.md#metadata-object) from a static [`layout.js`](/docs/app/api-reference/file-conventions/layout.md) or [`page.js`](/docs/app/api-reference/file-conventions/page.md) file. For example, to add a title and description to the blog route:

```tsx filename="app/blog/layout.tsx" switcher
import type { Metadata } from 'next'

export const metadata: Metadata = {
  title: 'My Blog',
  description: '...',
}

export default function Layout() {}
```

```jsx filename="app/blog/layout.js" switcher
export const metadata = {
  title: 'My Blog',
  description: '...',
}

export default function Layout() {}
```

You can view a full list of available options, in the [`generateMetadata` documentation](/docs/app/api-reference/functions/generate-metadata.md#metadata-fields).

## Generated metadata

You can use [`generateMetadata`](/docs/app/api-reference/functions/generate-metadata.md) function to `fetch` metadata that depends on data. For example, to fetch the title and description for a specific blog post:

```tsx filename="app/blog/[slug]/page.tsx" switcher
import type { Metadata, ResolvingMetadata } from 'next'

type Props = {
  params: Promise<{ slug: string }>
  searchParams: Promise<{ [key: string]: string | string[] | undefined }>
}

export async function generateMetadata(
  { params, searchParams }: Props,
  parent: ResolvingMetadata
): Promise<Metadata> {
  const slug = (await params).slug

  // fetch post information
  const post = await fetch(`https://api.vercel.app/blog/${slug}`).then((res) =>
    res.json()
  )

  return {
    title: post.title,
    description: post.description,
  }
}

export default function Page({ params, searchParams }: Props) {}
```

```jsx filename="app/blog/[slug]/page.js" switcher
export async function generateMetadata({ params, searchParams }, parent) {
  const slug = (await params).slug

  // fetch post information
  const post = await fetch(`https://api.vercel.app/blog/${slug}`).then((res) =>
    res.json()
  )

  return {
    title: post.title,
    description: post.description,
  }
}

export default function Page({ params, searchParams }) {}
```

### Streaming metadata

For dynamically rendered pages, Next.js streams metadata separately, injecting it into the HTML once `generateMetadata` resolves, without blocking UI rendering.

Streaming metadata improves perceived performance by allowing visual content to stream first.

Streaming metadata is **disabled for bots and crawlers** that expect metadata to be in the `<head>` tag (e.g. `Twitterbot`, `Slackbot`, `Bingbot`). These are detected by using the User Agent header from the incoming request.

You can customize or **disable** streaming metadata completely, with the [`htmlLimitedBots`](/docs/app/api-reference/config/next-config-js/htmlLimitedBots.md#disabling) option in your Next.js config file.

Statically rendered pages don’t use streaming since metadata is resolved at build time.

Learn more about [streaming metadata](/docs/app/api-reference/functions/generate-metadata.md#streaming-metadata).

### Memoizing data requests

There may be cases where you need to fetch the **same** data for metadata and the page itself. To avoid duplicate requests, you can use React's [`cache` function](https://react.dev/reference/react/cache) to memoize the return value and only fetch the data once. For example, to fetch the blog post information for both the metadata and the page:

```ts filename="app/lib/data.ts" highlight={5} switcher
import { cache } from 'react'
import { db } from '@/app/lib/db'

// getPost will be used twice, but execute only once
export const getPost = cache(async (slug: string) => {
  const res = await db.query.posts.findFirst({ where: eq(posts.slug, slug) })
  return res
})
```

```js filename="app/lib/data.js" highlight={5} switcher
import { cache } from 'react'
import { db } from '@/app/lib/db'

// getPost will be used twice, but execute only once
export const getPost = cache(async (slug) => {
  const res = await db.query.posts.findFirst({ where: eq(posts.slug, slug) })
  return res
})
```

```tsx filename="app/blog/[slug]/page.tsx" switcher
import { getPost } from '@/app/lib/data'

export async function generateMetadata({
  params,
}: {
  params: { slug: string }
}) {
  const post = await getPost(params.slug)
  return {
    title: post.title,
    description: post.description,
  }
}

export default async function Page({ params }: { params: { slug: string } }) {
  const post = await getPost(params.slug)
  return <div>{post.title}</div>
}
```

```jsx filename="app/blog/[slug]/page.js" switcher
import { getPost } from '@/app/lib/data'

export async function generateMetadata({ params }) {
  const post = await getPost(params.slug)
  return {
    title: post.title,
    description: post.description,
  }
}

export default async function Page({ params }) {
  const post = await getPost(params.slug)
  return <div>{post.title}</div>
}
```

## File-based metadata

The following special files are available for metadata:

* [favicon.ico, apple-icon.jpg, and icon.jpg](/docs/app/api-reference/file-conventions/metadata/app-icons.md)
* [opengraph-image.jpg and twitter-image.jpg](/docs/app/api-reference/file-conventions/metadata/opengraph-image.md)
* [robots.txt](/docs/app/api-reference/file-conventions/metadata/robots.md)
* [sitemap.xml](/docs/app/api-reference/file-conventions/metadata/sitemap.md)

You can use these for static metadata, or you can programmatically generate these files with code.

## Favicons

Favicons are small icons that represent your site in bookmarks and search results. To add a favicon to your application, create a `favicon.ico` and add to the root of the app folder.

![Favicon Special File inside the App Folder with sibling layout and page files](https://h8DxKfmAPhn8O0p3.public.blob.vercel-storage.com/docs/light/favicon-ico.png)

> You can also programmatically generate favicons using code. See the [favicon docs](/docs/app/api-reference/file-conventions/metadata/app-icons.md) for more information.

## Static Open Graph images

Open Graph (OG) images are images that represent your site in social media. To add a static OG image to your application, create a `opengraph-image.jpg` file in the root of the app folder.

![OG image special file inside the App folder with sibling layout and page files](https://h8DxKfmAPhn8O0p3.public.blob.vercel-storage.com/docs/light/opengraph-image.png)

You can also add OG images for specific routes by creating a `opengraph-image.jpg` deeper down the folder structure. For example, to create an OG image specific to the `/blog` route, add a `opengraph-image.jpg` file inside the `blog` folder.

![OG image special file inside the blog folder](https://h8DxKfmAPhn8O0p3.public.blob.vercel-storage.com/docs/light/opengraph-image-blog.png)

The more specific image will take precedence over any OG images above it in the folder structure.

> Other image formats such as `jpeg`, `png`, and `gif` are also supported. See the [Open Graph Image docs](/docs/app/api-reference/file-conventions/metadata/opengraph-image.md) for more information.

## Generated Open Graph images

The [`ImageResponse` constructor](/docs/app/api-reference/functions/image-response.md) allows you to generate dynamic images using JSX and CSS. This is useful for OG images that depend on data.

For example, to generate a unique OG image for each blog post, add a `opengraph-image.tsx` file inside the `blog` folder, and import the `ImageResponse` constructor from `next/og`:

```tsx filename="app/blog/[slug]/opengraph-image.tsx" switcher
import { ImageResponse } from 'next/og'
import { getPost } from '@/app/lib/data'

// Image metadata
export const size = {
  width: 1200,
  height: 630,
}

export const contentType = 'image/png'

// Image generation
export default async function Image({ params }: { params: { slug: string } }) {
  const post = await getPost(params.slug)

  return new ImageResponse(
    (
      // ImageResponse JSX element
      <div
        style={{
          fontSize: 128,
          background: 'white',
          width: '100%',
          height: '100%',
          display: 'flex',
          alignItems: 'center',
          justifyContent: 'center',
        }}
      >
        {post.title}
      </div>
    )
  )
}
```

```jsx filename="app/blog/[slug]/opengraph-image.js" switcher
import { ImageResponse } from 'next/og'
import { getPost } from '@/app/lib/data'

// Image metadata
export const size = {
  width: 1200,
  height: 630,
}

export const contentType = 'image/png'

// Image generation
export default async function Image({ params }) {
  const post = await getPost(params.slug)

  return new ImageResponse(
    (
      // ImageResponse JSX element
      <div
        style={{
          fontSize: 128,
          background: 'white',
          width: '100%',
          height: '100%',
          display: 'flex',
          alignItems: 'center',
          justifyContent: 'center',
        }}
      >
        {post.title}
      </div>
    )
  )
}
```

`ImageResponse` supports common CSS properties including flexbox and absolute positioning, custom fonts, text wrapping, centering, and nested images. [See the full list of supported CSS properties](/docs/app/api-reference/functions/image-response.md).

> **Good to know**:
>
> * Examples are available in the [Vercel OG Playground](https://og-playground.vercel.app/).
> * `ImageResponse` uses [`@vercel/og`](https://vercel.com/docs/og-image-generation), [`satori`](https://github.com/vercel/satori), and `resvg` to convert HTML and CSS into PNG.
> * Only flexbox and a subset of CSS properties are supported. Advanced layouts (e.g. `display: grid`) will not work.
## API Reference

Learn more about the Metadata APIs mentioned in this page.

- [generateMetadata](/docs/app/api-reference/functions/generate-metadata.md)
  - Learn how to add Metadata to your Next.js application for improved search engine optimization (SEO) and web shareability.
- [generateViewport](/docs/app/api-reference/functions/generate-viewport.md)
  - API Reference for the generateViewport function.
- [ImageResponse](/docs/app/api-reference/functions/image-response.md)
  - API Reference for the ImageResponse constructor.
- [Metadata Files](/docs/app/api-reference/file-conventions/metadata.md)
  - API documentation for the metadata file conventions.
- [favicon, icon, and apple-icon](/docs/app/api-reference/file-conventions/metadata/app-icons.md)
  - API Reference for the Favicon, Icon and Apple Icon file conventions.
- [opengraph-image and twitter-image](/docs/app/api-reference/file-conventions/metadata/opengraph-image.md)
  - API Reference for the Open Graph Image and Twitter Image file conventions.
- [robots.txt](/docs/app/api-reference/file-conventions/metadata/robots.md)
  - API Reference for robots.txt file.
- [sitemap.xml](/docs/app/api-reference/file-conventions/metadata/sitemap.md)
  - API Reference for the sitemap.xml file.
- [htmlLimitedBots](/docs/app/api-reference/config/next-config-js/htmlLimitedBots.md)
  - Specify a list of user agents that should receive blocking metadata.