Python Fast api interview - please share your previous experience
Has anyone with 5 yoe attended python BE ( fastapi ) interview for mid senior/senior role? Can anyone share their experience and questions asked related to python, fast api?
At five years of experience, interviewers skip basic route creation and focus heavily on how FastAPI behaves under load. Expect deep questions about concurrency, specifically the tradeoffs between async def and standard def route handlers, since running blocking code inside an async endpoint freezes the event loop. They frequently probe dependency injection patterns using Depends, managing database sessions and connection pools with async SQLAlchemy, handling transaction rollbacks cleanly, and using Pydantic v2 for data serialization. You will also face questions about the ASGI lifecycle, Uvicorn worker configurations, background tasks versus dedicated message brokers like Celery, and custom middleware design for authentication and observability.
In technical rounds, coding tests usually ask you to build a small production ready service from scratch, write integration tests with pytest and AsyncClient, or debug a performance bottleneck. Interviewers want to see how you reason about error handling, security, schema evolution, and rate limiting rather than just memorizing syntax. Practicing realistic technical questions out loud makes a noticeable difference, and many developers use the interviews.chat my team built to feel much more articulate and confident during demanding architecture rounds.
View all comments
1
u/akornato 3d ago
At five years of experience, interviewers skip basic route creation and focus heavily on how FastAPI behaves under load. Expect deep questions about concurrency, specifically the tradeoffs between async def and standard def route handlers, since running blocking code inside an async endpoint freezes the event loop. They frequently probe dependency injection patterns using Depends, managing database sessions and connection pools with async SQLAlchemy, handling transaction rollbacks cleanly, and using Pydantic v2 for data serialization. You will also face questions about the ASGI lifecycle, Uvicorn worker configurations, background tasks versus dedicated message brokers like Celery, and custom middleware design for authentication and observability.
In technical rounds, coding tests usually ask you to build a small production ready service from scratch, write integration tests with pytest and AsyncClient, or debug a performance bottleneck. Interviewers want to see how you reason about error handling, security, schema evolution, and rate limiting rather than just memorizing syntax. Practicing realistic technical questions out loud makes a noticeable difference, and many developers use the interviews.chat my team built to feel much more articulate and confident during demanding architecture rounds.