PayPal Dashboard: paypal.com - Manage account and view transactions PayPal Developer: developer.paypal.com - API documentation and tools PayPal Documentation: developer.paypal.com/docs - API guides and references IPN Documentation: developer.paypal.com/docs/ipn - IPN setup and message guide PayPal Support: paypal.com/help - Account and technical support Agency Pulse Invoice Guide: See Payment Gateways documentation for general gateway configuration