UML Usage Trends in Open Source Software

This research article investigates the historical and current usage of the Unified Modeling Language (UML) within open source software projects. The study analyzes approximately 13,000 GitHub repositories to assess the prevalence and evolution of UML over the past two decades. It identifies that only 4.2% of the analyzed repositories contain UML diagram files, indicating a significant underutilization of UML despite its importance in software design and documentation. The article discusses the factors contributing to this underutilization, including the decline in tool support and the stagnation of UML specifications. However, it also highlights a resurgence in UML's popularity associated with the rise of human-readable text-based formats like PlantUML and Mermaid. This resurgence presents new challenges, particularly regarding layout consistency and tool support. The article concludes by suggesting that a convergence of language specification evolution, standardization of text-based formats, and improved tooling is necessary for UML to enter a new phase of relevance in software engineering.