FileMaker Custom Functions for PayPal APIs provides a collection of custom functions for FileMaker Pro which provide direct access to PayPal's Web service APIs using nothing more than simple functions inside FileMaker calculations, just like any other FileMaker function. When the solution file starts, it loads a number of functions into your FileMaker system; you'll find them under External Functions from any calculation dialog. There are matching functions for each API call which PayPal provides in their NVP Web services. You simply choose a function and populate its parameters using your FileMaker data. The function will handle all communication with PayPal and return all response data back to the solution file in global fields so they're available for you to populate your own FileMaker tables/layouts accordingly.