FastAPI Interview Full
5 min read Quiz at the end
Interview topics: ASGI, Pydantic v2, Depends, async vs sync, OpenAPI, lifespan, 422 errors.
FastAPI Full Interview Guide
- ASGI vs WSGI — ASGI supports async; FastAPI uses Uvicorn/Starlette
- Pydantic v2 — Rust-powered; model_dump() replaces dict()
- Depends() — injects shared logic: auth, DB, config
- async def vs def — async for I/O; def runs in threadpool
- OpenAPI at /docs — auto-generated from type hints and Pydantic
- response_model — controls output schema, filters sensitive fields
- 422 — returned automatically on Pydantic validation failure
- BackgroundTasks vs Celery — BackgroundTasks for lightweight; Celery for heavy/retryable