LLM Best Practices

FastAPI vs Django

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Overview

Pick FastAPI for a service whose job is a typed HTTP API; pick Django for a product that needs an admin, relational models, auth, and server-rendered pages from the first commit. As of 2026-10-01 FastAPI is at 0.142 (native OpenTelemetry support arrived in 0.142.0 on 2026-09-29; it builds on Starlette) and Django is at 6.1 (released 2026-08-05; requires Python 3.12 to 3.14; Django 5.2 remains the current LTS and 6.2 is the next).

Comparison

DimensionFastAPIDjango 6.1
StyleFunctions with type hints; async-first on ASGIBatteries-included MVT framework; WSGI or ASGI
API docsOpenAPI and /docs generated from signatures and Pydantic modelsAdd Django REST Framework (3.18) with drf-spectacular, or Django Ninja
ORM and migrationsBring your own: SQLAlchemy and Alembic, or SQLModelBuilt-in ORM and makemigrations
AdminNoneBuilt-in admin
Auth, sessions, CSRF, permissionsAssemble from librariesBuilt-in
Background workBring your own queueBuilt-in django.tasks framework (6.0) needs external workers
Security extrasAdd middlewareBuilt-in Content Security Policy support (6.0)
TemplatesJinja2 if you add itDjango templates with template partials (6.0)

Pick FastAPI when

Pick FastAPI for API services consumed by a separate frontend or by other services.

  • Request and response validation, and the OpenAPI schema, come from the same type hints.
  • Async I/O fan-out: model inference, calls to LLM APIs, proxies.
  • A small service where assembling SQLAlchemy, Alembic, and auth yourself is acceptable.
  • Pin versions: FastAPI is still pre-1.0, so read release notes on upgrades. See fastapi.

Pick Django when

Pick Django when the admin and built-in components replace weeks of assembly.

  • Staff portals and CRUD over relational data via the admin; internal tools and content sites.
  • Auth, sessions, permissions, forms, and migrations that come tested together.
  • Server-rendered apps with htmx instead of a separate SPA. See htmx-vs-react.
  • A mature third-party ecosystem (SAML, OAuth, payments, multi-tenancy packages) and conventions that keep large teams aligned.
  • Django 6.1 adds fetch modes (FETCH_PEERS batches missing field loads to cut N+1 queries; FETCH_RAISE blocks them) and database-level on_delete options.

Combine

Run both on one Postgres database: Django owns the admin, models, and migrations; a FastAPI service exposes hot API paths. Share the schema through one migration tool only. Rewriting a Django app as FastAPI means rebuilding auth, admin, and migrations, so extract endpoints gradually. See postgres and migrations.

FAQ

Is FastAPI better than Django for APIs?

Pick FastAPI when the service’s job is a typed HTTP API consumed by a separate frontend or other services, since validation and the OpenAPI schema come from the same type hints. Pick Django when an admin, ORM, auth, and migrations should exist on day one.

Is FastAPI stable enough for production?

FastAPI is still pre-1.0 (0.142 as of 2026-10-01), so pin versions and read release notes on upgrades.

Can I use FastAPI and Django together?

Yes; run both on one Postgres database, with Django owning the admin, models, and migrations and FastAPI exposing hot API paths. Share the schema through one migration tool only.

Which Django version should I use?

Django 6.1 (released 2026-08-05) is current and requires Python 3.12 to 3.14. Django 5.2 remains the current LTS.

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