Introduction Modern financial systems operate under extreme demands: millions of transactions per day, strict latency requirements, and zero tolerance for downtime. Traditional monolithic architectures often struggle to meet these requirements due to tight coupling, limited scalability, and operational fragility. To address these challenges, many organizations are transitioning to event-driven microservices architectures. This approach enables systems to scale efficiently, remain resilient under failure, and process transactions in real time while maintaining strong security controls. This article explores how to design scalable and secure event-driven microservices systems tailored for high-volume financial workloads, focusing on architecture patterns, reliability strategies, and security best practices.…