Request headers

The following headers are sent to each Vercel deployment and can be used to process the request before sending back a response. These headers can be read from the Request object in your Vercel Function.

This header represents the domain name as it was accessed by the client. If the deployment has been assigned to a preview URL or production domain and the client visits the domain URL, it contains the custom domain instead of the underlying deployment URL.

This header contains a list of Vercel regions your request hit, as well as the region the function was executed in (for both Edge and Serverless).

It also allows Vercel to automatically prevent infinite loops.

This header is identical to the header.

This header represents the protocol of the forwarded server, typically in production and in development.

The public IP address of the client that made the request.

If you are trying to use Vercel behind a proxy, we currently overwrite the header and do not forward external IPs. This restriction is in place to prevent IP spoofing.

Enterprise customers can purchase and enable a trusted proxy to allow your custom IP. Contact us for more information.

This header is identical to the header. However, could be overwritten if you're using a proxy on top of Vercel.

This header is identical to the header.

This header represents the unique deployment, not the preview URL or production domain. For example, .

A two-character ISO 3166-1 code representing the continent associated with the location of the requester's public IP address. Codes used to identify continents are as follows:

• for Africa
• for Antarctica
• for Asia
• for Europe
• for North America
• for Oceania
• for South America

A two-character ISO 3166-1 country code for the country associated with the location of the requester's public IP address.

A string of up to three characters containing the region-portion of the ISO 3166-2 code for the first level region associated with the requester's public IP address. Some countries have two levels of subdivisions, in which case this is the least specific one. For example, in the United Kingdom this will be a country like "England", not a county like "Devon".

The city name for the location of the requester's public IP address. Non-ASCII characters are encoded according to RFC3986.

The latitude for the location of the requester's public IP address. For example, .

The longitude for the location of the requester's public IP address. For example, .

The name of the time zone for the location of the requester's public IP address in ICANN Time Zone Database name format such as .

The postal code close to the user's location.

The signature of the request. This header is used to verify that the request was sent by Vercel, and contains a hash signature you can use to validate the request body.