Spring Modulith

Spring Boot 3 baseline

Use the Spring Modulith 1.4 line with Boot 3.5; check the official compatibility matrix for older Boot 3 minors.

Apply within the existing architecture

Inspect the application root package, module boundaries and current dependency graph. Use direct subpackages as modules; keep their API at the module root and implementation in internal subpackages. Expose a named interface only for an intentional shared API. Use allowedDependencies when the architecture needs explicit dependency constraints. Avoid creating a generic shared module that every feature depends on.

Verify boundaries