Once you have set up your PayPal Business account for Digital Goods, you can request your PayPal API credentials. This tutorial illustrates how to obtain your PayPal API Credentials.
When logged into your PayPal Business or Sandbox Account, follow these 4 steps to access your API Username, Password & Signature.
- Step 1 – Click Profile
- Step 2 – Click API Access
- Step 3 – Click View API Signature
- Step 4 – Copy your Username, Password & Signature
PayPal Digital Goods PHP Library 