backend-fastapi

Clean Architecture in FastAPI separates business logic from framework concerns by organizing code into layers: domain entities, use cases, interfaces, and adapters. This ensures your core logic remains testable and independent of FastAPI, database, or external dependencies, making projects scalable and maintainable.

FastAPI's dependency injection system manages shared resources like database sessions and authentication through the Depends() function. Integrate it with Hexagonal or Clean Architecture patterns to inject repositories, services, and validators into endpoints, keeping concerns separated and enabling easy testing.

Use async SQLAlchemy sessions with FastAPI's async endpoints to perform non-blocking database queries. Combine with Alembic migrations for schema management and the repository pattern to abstract data access, ensuring your async endpoints remain responsive under load.

Yes. Domain-Driven Design in FastAPI structures code around business domains using entities, value objects, and aggregates in the domain layer, separate from FastAPI routes. This approach clarifies business rules, improves team communication, and makes backends resilient to framework changes.

Implement OAuth2 and JWT in FastAPI using Pydantic models for token validation and dependency injection to protect routes. Combine with explicit response models and error handling to create robust authentication that maintains separation between security logic and business endpoints.

Structured router organization using Clean or Hexagonal Architecture isolates features by domain, simplifies scaling, and enables parallel development. Pairing routers with repository patterns, Pydantic models, and dependency injection prevents entangled logic and reduces maintenance overhead.