Abstract: A payment gateway is implemented as a web service that utilizes a payment adapter plug-in model to support both synchronous payments (e.g., credit/debit card payments) and asynchronous payments (e.g., bank transfers) in which an interface to the payment gateway is provided to facilitate the development by a payment service provider or third party of a payment adapter that can plug into the gateway. The payment adapter enables the details of the payment service provider, credit card network, bank, etc. to be abstracted by mapping payment status from the provider to a standardized payment status that is utilized by the payment gateway. A payment gateway can then switch payment service providers by switching payment adapters.