Feature Based Clean Architecture. Part 1: How a NestJS Application Evolves Into an Unmaintainable State

Short summary

As NestJS projects scale, the feature-based module structure recommended by default degrades into unmaintainable code, forcing premature microservice migration. Using a Twitter-like backend case study, the article systematically traces how locally reasonable architectural decisions compound into codebase problems. It proposes Clean Architecture as a solution, backed by practical examples and formal reasoning.

• •Feature-based module structure works initially but degrades as codebases scale
• •Degradation leads to technical debt, maintenance costs, and premature microservice decisions
• •Clean Architecture prevents degradation through formal structural constraints

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