What is the Amazon Product Advertising API?
For developers:
How to get access to PA API?
From Amazon Associates Central website: https://affiliate-program.amazon.com/assoc_credentials/home:
How do I get access to PA API? In order to qualify for requesting access to PA API, you will need an associate account, you will have to complete 3 qualifying sales in the first 180 days and you will have to comply with the Operating Agreement. Once your account is approved as an associate account, you will see a 'Request for PA API access' button below. You can click the button to get access to PA API.