fastapi
FastAPI framework, high performance, easy to learn, fast to code, ready for production
What is it?
What it is
FastAPI is a modern Python web framework for building APIs with automatic OpenAPI docs, type hints, and async support. Built on Starlette and Pydantic.
Why it exists
Python needed a framework as fast as Node/Go for APIs, with great developer experience and automatic validation from type annotations.
Who should use it
Python developers building REST APIs, microservices, ML model servers, or backends for web/mobile apps.
Who should avoid it
Teams standardized on Django's admin/ORM ecosystem who do not need a dedicated API layer.
How it works
A quick walkthrough in plain English
How a FastAPI request works
Step 1 of 4
A client calls your API
A browser, mobile app, or another service sends an HTTP request.
Features
Advantages
- Excellent developer experience
- Auto-generated API documentation
- Strong typing reduces bugs
- Huge ecosystem compatibility
Disadvantages
- Not a full-stack framework (no built-in admin)
- Async requires understanding of Python concurrency
- ORM not included (use SQLAlchemy separately)
Installation
docker
FROM python:3.12-slim WORKDIR /app COPY requirements.txt . RUN pip install fastapi uvicorn COPY . . CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]
native
pip install "fastapi[standard]"
# main.py
from fastapi import FastAPI
app = FastAPI()
@app.get("/")
def read_root():
return {"Hello": "World"}
# uvicorn main:app --reloadFAQ
FastAPI vs Flask?
FastAPI is async-native, auto-validates with Pydantic, and generates OpenAPI docs. Flask is simpler and more mature.
Is FastAPI production-ready?
Yes. Used by Microsoft, Netflix, Uber, and many startups. Deploy with Uvicorn/Gunicorn behind nginx.
Does FastAPI support WebSockets?
Yes, natively via Starlette.
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