The PayPal Merchant SDK provides the following:
SetExpressCheckout API Operation (NVP/SOAP): The SetExpressCheckout API operation initiates an Express Checkout transaction.
DoDirectPayment API Operation (NVP/SOAP): The DoDirectPayment API Operation enables you to process a credit card payment.
MassPay API Operation (NVP/SOAP): The MassPay API operation makes a payment to one or more PayPal account holders.
GetRecurringPaymentsProfileDetails API Operation (NVP/SOAP): Obtain information about a recurring payments profile.
ManageRecurringPaymentsProfileStatus API Operation (NVP/SOAP): The ManageRecurringPaymentsProfileStatus API operation cancels, suspends, or reactivates a recurring payments profile.
UpdateRecurringPaymentsProfile API Operation (NVP/SOAP): The UpdateRecurringPaymentsProfile API operation updates a recurring payments profile.
DoReferenceTransaction API Operation (NVP/SOAP): The DoReferenceTransaction API operation processes a payment from a buyer’s account, which is identified by a previous transaction.