Modular Monolith Architecture in Cloud Environments: A Systematic Literature Review

Modular monolithic architecture (MMA) has recently emerged as a hybrid architecture that is positioned between traditional monoliths and microservices. It combines operational simplicity with modularity and maintainability. Although industry adoption of the architecture is growing, academic research on MMA remains fragmented and lacks systematic synthesis. This paper presents the first systematic literature review (SLR) of MMA in cloud environments. The review follows Kitchenham’s guidelines; we searched six major digital libraries for peer-reviewed studies published between 2020 and May 2025. From 369 retrieved records, we included 15 primary studies through a structured review protocol. Our synthesis highlights the problem of inconsistent terminology usage in the literature. It also identifies the architectural scope of MMA, and specifies the adoption drivers such as simplified deployment, maintainability, and reduced orchestration overhead. We also analyse implementation practices—including Domain-Driven Design (DDD), modular boundaries, and containerised deployment—and highlight comparative evidence showing MMA’s suitability when microservices introduce excessive complexity or costs. Key research gaps include the absence of consensus on a clear comprehensive definition, limited empirical benchmarking, and insufficient tools support. Thus, this study establishes a conceptual foundation for future research and provides practitioners with structured insights to inform architectural decisions in cloud-native environments.