Egencia Validation SPI
A service provider interface, not a consumable API - Egencia calls the customer. At checkout, when a traveller presses book, Egencia posts the booking payload to a web service the customer must build and implement, and the customer's response authorises or blocks the booking. The published contract is POST /v1/validateFields on https://apis.egencia.com/openconnect-validation-service. The integration burden sits on the customer's side, which is why an SPI raises switching cost even though the contract is published openly.
Documentation
APIReference
https://apis.egencia.com/openconnect-validation/docs/api-docs/validation
Documentation
https://www.egencia.com/openconnect-validation-service/v1/api-info