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

# Tracking requests

## Request identifier

Each API request is associated with a request ID. You can find this value in the response headers, under `RequestId` key. If you need to contact us about a specific request, providing the request identifier will ensure the fastest possible resolution.

## Idempotency keys

The Paybyrd API supports idempotency for safely retrying HTTP POST requests without accidentally duplicating operations.

An idempotency key is a unique value generated by the client that the server uses to recognize subsequent retries of the same request.

This is useful when no response is received due to a network connection error. Sending an idempotency key will allow you to repeat exactly the same request and obtain the response from the previous one.

To perform an idempotent request, provide an `idempotency-key` header as follows:

```bash theme={null}
curl -H 'idempotency-key: a5ce4eb7-86e9-4569-a722-091d06643201'
```

Paybyrd's idempotency works by saving the resulting status code and body of the first request made for any given idempotency key, regardless of whether it succeeded or failed. Subsequent requests with the same key return the same result, including 500 errors.

<Info>Using V4 UUIDs for idempotency keys will guarantee enough entropy and avoid collisions.</Info>

Idempotency keys expire after 24 hours after they are created. After expiry, a request with the same key is treated as a new operation.