What it is
FastAPI is a Python web framework built on Starlette for the HTTP layer and Pydantic for request validation, producing OpenAPI documentation automatically from your type hints. WebGrow24 uses FastAPI as our default Python API framework when the project needs async I/O, type-safe request and response models, and a minimal amount of boilerplate before a working endpoint exists. The async support matters for I/O-bound workloads common in Indian SMB applications: calling a GST filing API, fetching shipping rates from a logistics provider, or querying a database pool all release the event loop during the wait, allowing a single process to handle thousands of concurrent connections. Pydantic's runtime validation catches malformed data before it reaches your business logic, which means you write fewer defensive checks and get clearer error messages in API responses. For Indian SMBs, FastAPI's OpenAPI docs are useful for internal teams documenting integrations between services built by different vendors — a common pattern in Indian enterprise software where multiple agencies contribute to a single platform. We pair FastAPI with SQLAlchemy or Drizzle for database access, Celery or RQ for background jobs, and Pydantic for all request/response contracts. FastAPI is not the right fit for CPU-bound workloads where Python's GIL limits parallelism — a Go or Rust service handles those more efficiently.
Use cases
- Async REST APIs for web applications and mobile back-ends
- ML model serving endpoints with request validation and response serialisation
- Webhook handlers for payment gateways and logistics providers
- Internal tools and admin panels with fast iteration cycles
- Background job dispatchers connected to Celery or RQ workers
- Integration APIs connecting Indian government or banking services
- Real-time features via WebSockets backed by async Python
Integration patterns
Common integrations WebGrow24 connects with FastAPI:
- Pydantic (runtime data validation and serialisation from type hints)
- SQLAlchemy (async ORM for Postgres and MySQL with migration support)
- Drizzle ORM (lightweight TypeScript ORM for teams sharing schemas across stack)
- Celery (distributed task queue for heavy background processing)
- Redis (caching, rate limiting, and Celery broker)
- Uvicorn (ASGI server with hot reload for development)
- LangChain (LLM orchestration for AI-powered API endpoints)
- Python-multipart (file upload handling for form data)
- AWS Lambda (serverless deployment of FastAPI as an ASGI microservice)
- Supabase (managed Postgres with auth and real-time for FastAPI back-ends)