- [Express Checkout](https://developer.paypal.com/docs/classic/api/#express-checkout) - [SetExpressCheckout](https://developer.paypal.com/docs/classic/api/merchant/SetExpressCheckout_API_Operation_NVP/) - [GetExpressCheckoutDetails](https://developer.paypal.com/docs/classic/api/merchant/GetExpressCheckoutDetails_API_Operation_NVP/) - [DoExpressCheckoutPayment](https://developer.paypal.com/docs/classic/api/merchant/DoExpressCheckoutPayment_API_Operation_NVP/) - [RefundTransaction](https://developer.paypal.com/docs/classic/api/merchant/RefundTransaction_API_Operation_NVP/) - [CreateBillingAgreement](https://developer.paypal.com/docs/classic/api/merchant/CreateBillingAgreement_API_Operation_NVP/) - [CreateRecurringPaymentsProfile](https://developer.paypal.com/docs/classic/api/merchant/CreateRecurringPaymentsProfile_API_Operation_NVP/) - [GetRecurringPaymentsProfileDetails](https://developer.paypal.com/docs/classic/api/merchant/GetRecurringPaymentsProfileDetails_API_Operation_NVP/) - [UpdateRecurringPaymentsProfile](https://developer.paypal.com/docs/classic/api/merchant/UpdateRecurringPaymentsProfile_API_Operation_NVP/) - [ManageRecurringPaymentsProfileStatus](https://developer.paypal.com/docs/classic/api/merchant/ManageRecurringPaymentsProfileStatus_API_Operation_NVP/) - [Adaptive Payments](https://developer.paypal.com/docs/classic/api/adaptive-payments/) - [Pay](https://developer.paypal.com/docs/classic/api/adaptive-payments/Pay_API_Operation/)