Flask

Migrating from Flask or Django to FastAPI requires replacing familiar tools: `requests` must be replaced with `httpx` for async operations, Django REST Framework serializers must become Pydantic models, and the async paradigm shift is non-trivial. FastAPI lacks the built-in ORM and admin panel developers relied on.

FastAPI applications consume more resources compared to lighter frameworks like Flask, Bottle, and Falcon, which can be problematic for projects with strict resource allocation restrictions.