I'm currently working on a large-scale backend project in Node.js and looking for the best way to organize the project file structure and manage dependencies. What principles do you find most effective? Do you prefer separating code by functional modules or by layers (controllers, services, models)? How do you usually structure configurations and environments? Are there proven practices to simplify module imports and avoid circular dependencies? Share your experience and recommendations, which tools help maintain clean code. 👀
The optimal organization of file structure and dependencies in large Node.js projects
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For large Node projects, I usually prefer a **feature-based structure**, where each module groups controllers, services, and models related to a single business feature. This approach is similar to how Angular or NestJS organize "modules," but unlike the classic layer-based (MVC) separation, it reduces cross-layer imports and makes refactoring easier. In NestJS, for example, the controller-service-repository layers are explicitly separated, which is convenient for microservices, but in large projects, it often leads to "deep" nesting and code duplication if each layer is placed in a separate folder. The feature-based structure, on the other hand, keeps everything needed for a specific domain in one place, while common services (logging, caching, auth) are extracted into separate "core" modules—this simplifies imports (via aliases in `tsconfig.json` or `module-alias`) and prevents circular dependencies.
As for configuration, I use **dotenv + a config package**: I keep `default.json`, `production.json`, and `development.json` in the `config/` directory, and environment variables are picked up via `process.env`. To simplify imports, I add aliases (`@services`, `@models`, `@features`), and where possible, I create "barrel" files (`index.ts`) in each module so that external code imports a single file instead of multiple separate ones. To eliminate circular dependencies, I introduce **interfaces/contracts** between services and use dependency injection through a container (e.g., `typedi`), which forces modules to depend on abstractions rather than concrete implementations. This set of practices usually keeps the code clean and makes project scaling easier.