Modularisation and the management of IT architecture complexity

Managing IT architecture complexity is crucial for organisations striving for efficiency, flexibility, and agility. This paper examines modularisation as a strategy to address IT architecture complexity through a case study at a European bank. We explore three key design choices in modularisation: level of granularity, standardisation of interfaces, and unification of data, and their impacts on structural, dynamic, and subjective complexity. Our findings reveal that these design choices involve trade-offs, where optimising one dimension may exacerbate another. Our findings lead to a conceptualisation of the relationship between modularisation and complexity as one in which design choices set in motion patterns of shifts within, and interactions between, different forms of complexity. Thus, this study provides a nuanced understanding of how modularisation influences IT architecture complexity, offering valuable insights for organisations seeking to manage complexity effectively. By unpacking the shifts and interactions shaping complexity, we contribute to the literature on IT architecture complexity and modularisation, highlighting the importance of a multi-level perspective in understanding the consequences of modularisation design choices.