---
description: Add custom HTTP headers to your Next.js app.
---

# Headers

> This feature was introduced in [Next.js 9.5](https://nextjs.org/blog/next-9-5) and up. If you’re using older versions of Next.js, please upgrade before trying it out.

<details open>
  <summary><b>Examples</b></summary>
  <ul>
    <li><a href="https://github.com/vercel/next.js/tree/canary/examples/headers">Headers</a></li>
  </ul>
</details>

Headers allow you to set custom HTTP headers for an incoming request path.

To set custom HTTP headers you can use the `headers` key in `next.config.js`:

```js
module.exports = {
  async headers() {
    return [
      {
        source: '/about',
        headers: [
          {
            key: 'x-custom-header',
            value: 'my custom header value',
          },
          {
            key: 'x-another-custom-header',
            value: 'my other custom header value',
          },
        ],
      },
    ]
  },
}
```

`headers` is an async function that expects an array to be returned holding objects with `source` and `headers` properties:

- `source` is the incoming request path pattern.
- `headers` is an array of header objects with the `key` and `value` properties.
- `basePath`: `false` or `undefined` - if false the basePath won't be included when matching, can be used for external rewrites only.
- `locale`: `false` or `undefined` - whether the locale should not be included when matching.
- `has` is an array of [has objects](#header-cookie-and-query-matching) with the `type`, `key` and `value` properties.

Headers are checked before the filesystem which includes pages and `/public` files.

## Header Overriding Behavior

If two headers match the same path and set the same header key, the last header key will override the first. Using the below headers, the path `/hello` will result in the header `x-hello` being `world` due to the last header value set being `world`.

```js
module.exports = {
  async headers() {
    return [
      {
        source: '/:path*',
        headers: [
          {
            key: 'x-hello',
            value: 'there',
          },
        ],
      },
      {
        source: '/hello',
        headers: [
          {
            key: 'x-hello',
            value: 'world',
          },
        ],
      },
    ],
  },
}
```

## Path Matching

Path matches are allowed, for example `/blog/:slug` will match `/blog/hello-world` (no nested paths):

```js
module.exports = {
  async headers() {
    return [
      {
        source: '/blog/:slug',
        headers: [
          {
            key: 'x-slug',
            value: ':slug', // Matched parameters can be used in the value
          },
          {
            key: 'x-slug-:slug', // Matched parameters can be used in the key
            value: 'my other custom header value',
          },
        ],
      },
    ],
  },
}
```

### Wildcard Path Matching

To match a wildcard path you can use `*` after a parameter, for example `/blog/:slug*` will match `/blog/a/b/c/d/hello-world`:

```js
module.exports = {
  async headers() {
    return [
      {
        source: '/blog/:slug*',
        headers: [
          {
            key: 'x-slug',
            value: ':slug*', // Matched parameters can be used in the value
          },
          {
            key: 'x-slug-:slug*', // Matched parameters can be used in the key
            value: 'my other custom header value',
          },
        ],
      },
    ],
  },
}
```

### Regex Path Matching

To match a regex path you can wrap the regex in parenthesis after a parameter, for example `/blog/:slug(\\d{1,})` will match `/blog/123` but not `/blog/abc`:

```js
module.exports = {
  async headers() {
    return [
      {
        source: '/blog/:post(\\d{1,})',
        headers: [
          {
            key: 'x-post',
            value: ':post',
          },
        ],
      },
    ],
  },
}
```

## Header, Cookie, and Query Matching

To only apply a header when either header, cookie, or query values also match the `has` field can be used. Both the `source` and all `has` items must match for the header to be applied.

`has` items have the following fields:

- `type`: `String` - must be either `header`, `cookie`, `host`, or `query`.
- `key`: `String` - the key from the selected type to match against.
- `value`: `String` or `undefined` - the value to check for, if undefined any value will match. A regex like string can be used to capture a specific part of the value, e.g. if the value `first-(?<paramName>.*)` is used for `first-second` then `second` will be usable in the destination with `:paramName`.

```js
module.exports = {
  async headers() {
    return [
      // if the header `x-add-header` is present,
      // the `x-another-header` header will be applied
      {
        source: '/:path*',
        has: [
          {
            type: 'header',
            key: 'x-add-header',
          },
        ],
        headers: [
          {
            key: 'x-another-header',
            value: 'hello',
          },
        ],
      },
      // if the source, query, and cookie are matched,
      // the `x-authorized` header will be applied
      {
        source: '/specific/:path*',
        has: [
          {
            type: 'query',
            key: 'page',
            value: 'home',
          },
          {
            type: 'cookie',
            key: 'authorized',
            value: 'true',
          },
        ],
        headers: [
          {
            key: 'x-authorized',
            value: ':authorized',
          },
        ],
      },
      // if the header `x-authorized` is present and
      // contains a matching value, the `x-another-header` will be applied
      {
        source: '/:path*',
        has: [
          {
            type: 'header',
            key: 'x-authorized',
            value: '(?<authorized>yes|true)',
          },
        ],
        headers: [
          {
            key: 'x-another-header',
            value: ':authorized',
          },
        ],
      },
      // if the host is `example.com`,
      // this header will be applied
      {
        source: '/:path*',
        has: [
          {
            type: 'host',
            value: 'example.com',
          },
        ],
        headers: [
          {
            key: 'x-another-header',
            value: ':authorized',
          },
        ],
      },
    ]
  },
}
```

### Headers with basePath support

When leveraging [`basePath` support](/docs/api-reference/next.config.js/basepath.md) with headers each `source` is automatically prefixed with the `basePath` unless you add `basePath: false` to the header:

```js
module.exports = {
  basePath: '/docs',

  async headers() {
    return [
      {
        source: '/with-basePath', // becomes /docs/with-basePath
        headers: [
          {
            key: 'x-hello',
            value: 'world',
          },
        ],
      },
      {
        source: '/without-basePath', // is not modified since basePath: false is set
        headers: [
          {
            key: 'x-hello',
            value: 'world',
          },
        ],
        basePath: false,
      },
    ]
  },
}
```

### Headers with i18n support

When leveraging [`i18n` support](/docs/advanced-features/i18n-routing.md) with headers each `source` is automatically prefixed to handle the configured `locales` unless you add `locale: false` to the header. If `locale: false` is used you must prefix the `source` with a locale for it to be matched correctly.

```js
module.exports = {
  i18n: {
    locales: ['en', 'fr', 'de'],
    defaultLocale: 'en',
  },

  async headers() {
    return [
      {
        source: '/with-locale', // automatically handles all locales
        headers: [
          {
            key: 'x-hello',
            value: 'world',
          },
        ],
      },
      {
        // does not handle locales automatically since locale: false is set
        source: '/nl/with-locale-manual',
        locale: false,
        headers: [
          {
            key: 'x-hello',
            value: 'world',
          },
        ],
      },
      {
        // this matches '/' since `en` is the defaultLocale
        source: '/en',
        locale: false,
        headers: [
          {
            key: 'x-hello',
            value: 'world',
          },
        ],
      },
      {
        // this gets converted to /(en|fr|de)/(.*) so will not match the top-level
        // `/` or `/fr` routes like /:path* would
        source: '/(.*)',
        headers: [
          {
            key: 'x-hello',
            value: 'worlld',
          },
        ],
      },
    ]
  },
}
```

### Cache-Control

Cache-Control headers set in next.config.js will be overwritten in production to ensure that static assets can be cached effectively. If you need to revalidate the cache of a page that has been [statically generated](https://nextjs.org/docs/basic-features/pages#static-generation-recommended), you can do so by setting `revalidate` in the page's [`getStaticProps`](https://nextjs.org/docs/basic-features/data-fetching#getstaticprops-static-generation) function.
