Use this section to understand the foundational building blocks of Encryption, Idempotency, and HTTP API Standards which apply to all Google Standard Payments APIs. Once you feel comfortable there you'll find references to the specific APIs of the service you're integrating with.
Find helpful definition of terms in the Glossary.
For overview of the flows, go to the Concepts section.
When you're ready to dive into integrating start with the Implementation Steps.
More information about testing your endpoints using Amplecash, or Cash tester Amplecash tool for a Cash FOP can be found under Testing.