Operational systems for the FinTech sector require innovative approaches to address the unique challenges posed by the need for speed, scalability, accuracy, and reliability. This discussion highlights five architectural best practices for developing effective FinTech systems: decomposing business logic into microservices, opting for asynchronous, event-driven communications, securing a single source of truth with event sourcing, implementing queries with Command Query Responsibility Segregation (CQRS) and materialized views, and deploying microservices as containerized or serverless workloads. These strategies help reduce complexity and enhance the efficiency of FinTech systems while facilitating compliance with evolving regulations. The text underscores the importance of using an event broker like Redpanda, which offers advantages such as cost efficiency, high throughput, and compatibility with Apache Kafka APIs, making it an ideal choice for FinTech systems. By adopting these architectural guidelines, FinTech companies can improve their systems' performance and reliability while supporting rapid market delivery and innovation.