Payment gateway for e-commerce

Challenge. A growing e-commerce project needed a payment gateway that could survive sharp sale-day peaks with no lost or duplicated transactions.

Solution. We built processing with idempotency guarantees, queues and the outbox pattern, horizontal scaling of stateless services and inline anti-fraud, with analytics moved to a separate store.

Result. The system steadily handles 5000+ TPS at 99.99% uptime, with zero payment-loss incidents on peak sale days.