FastAPI Interview Questions
FastAPI interview questions on async routing, Pydantic validation, dependency injection, OAuth2 security, database integration and deployment — the go-to Python framework for production APIs.
Topics
- FundamentalsAsync/await, ASGI, the request lifecycle and OpenAPI — the FastAPI foundation every interviewer expects you to understand cold. 5 subtopics
- Routing & ParametersPath parameters, query strings, request bodies, response models and APIRouter — how FastAPI maps URLs to handlers and shapes their inputs and outputs. 4 subtopics
- Pydantic & ValidationBaseModel, field validators, serialization and BaseSettings — Pydantic v2 powers FastAPI's entire request validation and config story. 4 subtopics
- Dependency InjectionDepends(), yield dependencies, class-based deps and lifespan — FastAPI's DI system is one of its most interview-tested features. 3 subtopics
- Security & AuthOAuth2, JWT tokens and API keys — common FastAPI auth patterns that come up in both system-design and code-review interview rounds. 3 subtopics
- Database IntegrationSQLAlchemy sync and async sessions, Alembic migrations — how to wire a database into a FastAPI app without blocking the event loop. 3 subtopics
- TestingTestClient, AsyncClient, pytest-asyncio and dependency overrides — the testing patterns FastAPI teams reach for in production codebases. 3 subtopics
- Deployment & MiddlewareUvicorn, Gunicorn, CORS middleware and BackgroundTasks — deploying FastAPI apps and tuning them for production traffic. 3 subtopics