PayPal Certified Developer Certification is a certification in which after you pass it, you can claim yourself as a "PayPal Certified Developer" and be listed in PayPal Certified Developer Directory.
At the PayPal site, you can find an overview of the certification, FAQ, and the steps to becoming certified.
The PayPal certification is intended for developers wanting to use PayPal in building eCommerce solutions. The certification involves a fee and 90-minute multiple-choice online exam.
The exam covers Website Payment Pro integration, Direct Payment API, Name-Value Pair interface, Express Checkout, Sandbox Testing, and more.
See the PayPal Developer Certification Study Guide for details and study material.
Other references that you may want to study are ...
