- [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/)