# Endpoint guide
source: https://developer.mastercard.com/cross-border-services/documentation/use-cases/value-added-services/endpoint-guide/index.md

Use the [Endpoint Guide API](https://developer.mastercard.com/cross-border-services/documentation/api-ref/value-added-services/endpoint-guide-adapter_api/index.md) to understand the information required for a Payment corridor before submitting a Quote or Payment request.

**Preconditions**

* You know the Payment Type.
* You know the destination country and destination currency.
* You know the destination payment instrument.

**Example sequence**
Diagram vas-endpoint-guide-sequence

**Workflow**

1. The Customer requests the corridor data requirements from the [Endpoint Guide API](https://developer.mastercard.com/cross-border-services/documentation/api-ref/value-added-services/endpoint-guide-adapter_api/index.md), providing the Payment Type, destination country, destination currency and destination payment instrument.
2. The Endpoint Guide API retrieves the core and additional data requirements.
3. The API returns either the corridor data requirements when the corridor is supported, or an error when the corridor is not supported or the request is invalid. Use the response to identify the mandatory, optional and conditional fields required for the Quote or Payment request.

**Endpoint**

API Reference: `GET /crossborder/endpoint-guide/specifications`

Note: The Endpoint Guide API call should not be integrated into the Payment API flow. Cache the Endpoint Guide specifications and refresh them once a week. Refer to Customer Notices for Payout Service Updates to determine whether an additional refresh is required.