Payments Gateway Processing

Payments gateway processing is the intersection of backend engineering and financial compliance. It's the skill of integrating third-party payment processors (Stripe, PayPal, Adyen, Square) into applications so customers can buy things. You manage API authentication, handle webhooks, reconcile transactions, manage failed payments, and ensure PCI-DSS compliance. Payment processing isn't just about making a API call—it's orchestrating a complex dance: authorization, settlement, disputes, refunds, currency conversion, and regulatory compliance. Most applications get it wrong, losing 5-10% of revenue to failed payments, chargebacks, and poor error handling.