> ## Documentation Index
> Fetch the complete documentation index at: https://developer.uphold.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Common headers

> Reference for the common request and response headers used across Uphold REST APIs to pass user context, idempotency keys, and other request metadata.

The REST APIs use custom headers for passing context in requests and returning useful metadata in responses. This page documents the headers that are common to all endpoints. Some endpoints may include additional headers specific to their functionality.

## Request headers

### User context

The REST APIs are not meant to be called directly by your frontend applications, but rather by your backend systems. A side-effect of this is that Uphold is unable to extract context of users' requests, such as the user's IP address, user agent, and other information that would be typically available otherwise.

To address this, Uphold provides a way for you to pass users' context via headers. This context enriches the request and provides better insights into end users' actions. In fact, **certain APIs require** parts of the context to be present in order to function correctly, so you should include it in all API requests made on behalf of your end users.

Include the following headers in your API requests:

* `X-Uphold-User-Ip`: The IP address of the end user.
* `X-Uphold-User-Agent`: The user agent string of the end user's device.
* `X-Uphold-User-Origin`: The original `Origin` header if the request was made from a browser.
* `X-Uphold-User-Country`: The country code ([ISO 3166](https://en.wikipedia.org/wiki/ISO_3166-2) - two letter) associated with the geolocation of the end user.
* `X-Uphold-User-Subdivision`: The subdivision code ([ISO 3166](https://en.wikipedia.org/wiki/ISO_3166-2)) associated with the geolocation of the end user.
* `X-Uphold-User-City`: The city associated with the geolocation of the end user.

## Response headers

### Request id

Every API response includes an `X-Uphold-Request-Id` header containing a unique identifier for the request. You can use this identifier when contacting Uphold support to help troubleshoot specific requests.

```
X-Uphold-Request-Id: 9d71b4edeb46c8f9-MAD
```