An Empirical Comparison of Monolithic and Microservices Architectures for an E-Commerce Application

This paper presents an empirical performance comparison of monolithic and microservices architectures for an e-commerce application. Using k6 load testing at 50 and 100 virtual users, we demonstrate that microservices achieve 5.4% higher throughput, 25% lower average latency, and 39% lower p95 latency at 100 VUs, while exhibiting different failure modes. The monolith shows consistent order-creation failures (~0.7% error rate), whereas microservices failures are transient and service-specific. This study provides quantitative evidence that architectural decomposition can improve scalability and tail latency under stress, with implications for software architecture decision-making.