A good API is a contract your clients depend on. This guide covers how to build production Python APIs that mobile apps, SPAs, and integrations can rely on — from framework choice to testing.
FastAPI or Django REST Framework?
FastAPI for async, high-throughput, and ML-serving APIs with Pydantic validation and automatic docs. DRF when you want Django's ORM, admin, and auth beside the API. Pick per workload.
The essentials of a production API
- Token auth (JWT/OAuth2) with refresh and per-resource permissions
- Strict validation — Pydantic models or DRF serializers
- Versioning (/api/v1/) with a deprecation policy
- Consistent error envelopes and pagination
- OpenAPI/Swagger docs and Postman collections
- Async workers (Celery or async) for webhooks and heavy jobs
Testing that protects mobile releases
Write pytest feature tests on every endpoint — happy path, validation errors, auth failures, and permission boundaries. Contract tests catch accidental breaks before app store releases.
Security must-haves
Rate limiting, IDOR tests on multi-tenant data, mass-assignment guards, and secrets in environment vaults — validated in CI before deploy.