Why I Moved From Django to FastAPI (And When I Still Use Django)

I started with Django in 2016. It was the framework that taught me what a 'batteries included' framework actually meant — admin panel, ORM, migrations, auth, all wired together. For four years it was my default answer to every Python web project.

What changed

The shift started when I joined a team building a real-time communication platform. We needed WebSocket support, async task processing, and sub-100ms API responses at scale. Django could handle all of this, but it felt like fighting the framework — ASGI support was bolted on, and the ORM is fundamentally synchronous.

What FastAPI does better

Async-native from day one. Async/await works everywhere without fighting the ORM or middleware stack.
Dependency injection is a first-class citizen. FastAPI's Depends() system makes auth, DB sessions, and feature flags clean and testable.
Automatic OpenAPI docs. The interactive /docs page is generated from your type hints — no extra work.
Pydantic v2 integration. Request validation, serialization, and response models all share the same schema definitions.
Performance. Benchmarks show FastAPI 2–3x faster than Django REST Framework on equivalent endpoints.

What Django still does better

The admin panel. Django admin is unmatched for internal tooling. Building the same thing in FastAPI takes days.
The ORM for complex queries. Django's ORM with select_related and prefetch_related is still the most ergonomic way to work with relational data. SQLAlchemy 2.x comes close, but the learning curve is steeper.
Built-in auth. Django's auth system — sessions, groups, permissions — is battle-tested and covers 90% of use cases out of the box.
Migrations. Django migrations are the best database migration DX I've used. Alembic is fine, but it requires more manual work.
Ecosystem. Thousands of reusable apps: django-allauth, django-storages, django-celery-beat. FastAPI is catching up, but it's not there yet.

My decision framework

I use FastAPI when: the project is API-first with heavy async requirements, I'm building microservices, or performance is a primary concern. I use Django when: there's an admin-heavy workflow, the team is more comfortable with Django's conventions, or I need to ship quickly and the built-in batteries matter.

Migration strategy

If you're migrating an existing Django project, don't do a big-bang rewrite. Introduce FastAPI as a sidecar service for new high-traffic endpoints, keep Django for the admin and complex ORM queries, and share the database between them. Gradually route traffic to the FastAPI service as confidence grows.

python

# Coexistence: FastAPI handles the API layer,
# Django still owns admin + ORM-heavy operations

# fastapi_app/routers/calls.py
@router.post("/calls", response_model=CallResponse)
async def create_call(payload: CallCreate) -> CallResponse:
    # Motor directly to same MongoDB the Django app uses
    doc = await db.calls.insert_one(payload.model_dump())
    return CallResponse(id=str(doc.inserted_id), **payload.model_dump())

The honest answer

Both frameworks are excellent. The real answer is: use whichever one your team knows well and fits the project's requirements. I choose FastAPI for new API-first projects because async-native feels right for 2025, but I have deep respect for what Django represents — a framework that has shipped millions of successful applications.