Driver 01
WSGI concurrency limits
Synchronous workers blocked on external API calls and slow database queries.
Migration playbook: Django (sync) → FastAPI (async)
Django to FastAPI async API modernization
Move blocking Django endpoints to asynchronous FastAPI services where concurrency matters — AI streaming, slow upstream calls — while Django keeps the admin.
Migration drivers
Why teams make this move
Driver 02
Streaming AI responses
Needing Server-Sent Events and WebSockets for generative AI features.
Driver 03
Memory per worker
Each extra synchronous worker adds a whole process's memory, so concurrency gets expensive.
Execution sequence
How the migration runs
Each phase ends with a check you can verify — data parity, error rates, latency — and the rollback path is agreed before any traffic moves.
- 01Phase
Models to SQLAlchemy 2.0
Porting Django ORM models to async SQLAlchemy 2.0, with Alembic for migrations.
- 02Phase
Pydantic v2 schemas
Replacing Django forms and serializers with Pydantic v2 models.
- 03Phase
Incremental reverse-proxy routing
Routing high-throughput endpoints to FastAPI while administrative tools stay on Django.
- 04Phase
Async switchover
Running on Uvicorn with uvloop and pooled asyncpg connections.
Risk prevention
Pitfalls that derail this migration
Risk 01
Blocking calls in async routes
Calling synchronous HTTP clients or blocking file I/O inside async def routes, which stalls the event loop.
Risk 02
Alembic vs Django migration drift
Subtle column default or constraint differences introduced during schema translation.
Risk 03
Session and token mismatches
Not standardizing JWT signing keys and claims across the Django and FastAPI backends.
Before and after
What we measure
We take a baseline before any change and report the same numbers after cutover, from your own tools. They are the evidence of whether the migration worked — not figures promised in advance.
- Concurrency
- Requests in flight per instance under a load test
- p95 latency
- Migrated endpoints, before and after
- Memory
- Memory per container at the same traffic
Questions
Frequently asked migration questions
Yes. A common architecture keeps Django for administrative dashboards while FastAPI handles high-concurrency public API traffic against the same PostgreSQL database.
FastAPI is async-native, validates with Pydantic v2 (its core is written in Rust) and generates OpenAPI docs from type hints. DRF brings Django's ORM, admin and a mature ecosystem. The speed difference matters most on I/O-bound and validation-heavy endpoints — measure yours before moving everything.
Rehearse the cutover before the real one
Tell us about your data volume, traffic and timeline. An engineer will reply within one business day to set up a call about the migration plan and its rollback path.