With the rapid pace of digital transformation, the retail industry is increasingly depending on real-time, scalable, and resilient systems to manage financial transactions, analyze customer behavior, and streamline order processing. This literature review explores how modern event-driven and microservices-based architectures, particularly those leveraging Apache Kafka, Spring Boot, MongoDB, and Kubernetes are transforming retail and financial systems. By systematically reviewing academic publications, technical white papers, and industry reports from recent years, this study synthesizes key themes and implementation strategies. The analysis reveals that technologies like Kafka and Spring Boot are instrumental in building low-latency, event-driven applications that support real-time analytics and fraud detection, while MongoDB, when deployed on Kubernetes, ensures fault tolerance and high availability in inventory and transaction systems. Kubernetes itself plays a crucial role in automating deployment and scaling of microservices. These findings provide valuable insights for industry practitioners aiming to design scalable infrastructures, identify research opportunities in hybrid deployment models, and offer educators a foundation to integrate modern system architectures into professional and technical communication training.