Architecture | Hexagonal vs Clean Architecture in Spring Boot
Once you move beyond simple CRUD services, architecture choices start to matter. Two patterns that are often mentioned together are Hexagonal Architecture and Clean Architecture. They share common goals, but they are not the same—and choosing between them (or blending them) has real consequences for Spring Boot systems.
The Shared Goal
Both architectures aim to:
- Isolate business logic
- Prevent framework lock-in
- Improve testability
- Support long-term change
Where they differ is structure and emphasis.
Hexagonal Architecture
Hexagonal Architecture focuses on interaction points. Everything outside the domain is an adapter, whether it’s HTTP, Kafka, or persistence. The model is interaction-driven and works exceptionally well for event-driven systems.
Strengths:
- Excellent for Kafka and messaging-heavy platforms
- Simple mental model
- Natural fit for microservices
Clean Architecture
Clean Architecture introduces concentric layers with strict dependency rules. It emphasises use cases and entities and can be more prescriptive in structure.
Strengths:
- Clear separation of concerns
- Strong guidance for large teams
- Explicit boundaries for complex domains
Which I Use and Why
In Spring Boot systems, I tend to start with Hexagonal Architecture. It gives me flexibility without unnecessary ceremony. When systems grow large or teams expand, I selectively introduce Clean Architecture concepts where they add clarity.
Final Thoughts
You don’t need to choose sides. The best systems borrow pragmatically. Hexagonal Architecture provides a strong foundation, and Clean Architecture offers additional structure when complexity demands it. The key is protecting your domain from the churn of frameworks and infrastructure.