Modular Maturity Index

The Modular Maturity Index (MMI) — associated with Dr. Carola Lilienthal — provides a structured way to assess “modularity” based on observable criteria rather than gut feel. It makes architectural quality visible through measurable signals such as coupling, cohesion, dependency structures, and change dynamics, and turns the findings into actionable improvement priorities. MMI is typically used when teams must operate and evolve a system over time: modularity directly affects changeability, testability, delivery speed, and risk. A practical MMI assessment combines (a) a consistent module/domain view (e.g., packages, components, services, or modules in a DDD sense) with (b) a metrics set and (c) a maturity model that translates results into actionable levels. Importantly, MMI is not a tool and not a single metric. It is a concept for architectural diagnosis and steering. Value emerges when teams run measurement as a continuous feedback loop: metrics are not used to “grade people” but as early indicators of technical risk and as navigation aids for refactoring, improving domain boundaries, and reducing coupling.