Setting up PayPal API credentials for Subscription Addon

Please use the NVP/SOAP API integration (Classic) in PayPal

  1. Login to your PayPal Business Account
  2. Go to Account settings
  3. Find API access and click update
  4. Next go to NVP/SOAP API integration (Classic) and click manage API credentials
  5. If you have never created an application a Security Check may be required
  6. You can create the API Signature or View the API Credentials after the Security Check
  7. After you have manage to generate the API credentials, copy your Paypal API Username, Paypal API Password, Paypal API Signature and paste them into Projectopia’s Settings -> Payment Gateway accordingly
  8. Next proceed to setup the IPN notification.
  9. The PayPal IPN notification URL will be in the following format.
  10. You may want to signup for PayPal sandbox for testing before going live.


If you have encounter the error message “Security header is not valid”, please use the following troubleshooting steps.

  1. If you have enabled sandbox, please make sure that you are using API credentials generated from your PayPal Sandbox business account.
  2. If you are going live, please uncheck sandbox and use API credentials generated from your PayPal business account.
  3. Make sure there is no empty spacing at the end of your option values.
  4. Your API credentials may have changed, please login to your PayPal account to double check.