FastAPI Has a Free Python Framework — Auto-Generated Docs and 3x Faster Than Flask

FastAPI generates Swagger docs from Python type hints, validates requests automatically, and runs on ASGI for async performance. Why FastAPI Replaced Flask Flask: no type hints, no validation, no auto-docs, no async support. You add extensions for everything. FastAPI: type hints ARE the validation, documentation, and serialization. What You Get for Free from fastapi import FastAPI from pydantic import BaseModel app = FastAPI () class User ( BaseModel ): name : str email : str age : int | None = None @app.get ( ' /users/{user_id} ' ) async def get_user ( user_id : int ): return { ' user_id ' : user_id , ' name ' : ' Alice ' } @app.post ( ' /users ' ) async def create_user ( user : User ): return user This gives you: Swagger UI at /docs — interactive API documentation ReDoc at /redoc — alternative documentation Request validation — user_id must be int, body must match User schema Response serialization — Pydantic handles JSON encoding Async support — async def for non-blocking I/O Quick