FastAPI Crash Course: Build a Production-Ready API (Auth + DB + Docs)

FastAPI gives you speed (async), type safety (Pydantic), and built-in docs (Swagger UI) in a single framework. It’s the best “default” choice for Python APIs in 2025. Let’s build a realistic mini-project.

Project Setup

mkdir fastapi-app && cd fastapi-app
python -m venv .venv
source .venv/bin/activate
pip install fastapi uvicorn[standard] sqlalchemy pydantic python-jose[cryptography] passlib[bcrypt]

Recommended Structure

app/
  main.py
  db.py
  models.py
  schemas.py
  auth.py
  routes/
    users.py
    items.py

Database Setup (SQLAlchemy)

# app/db.py
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

DATABASE_URL = "sqlite:///./app.db"
engine = create_engine(DATABASE_URL, connect_args={"check_same_thread": False})
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

Pydantic Schemas

# app/schemas.py
from pydantic import BaseModel, EmailStr

class UserCreate(BaseModel):
    email: EmailStr
    password: str

class UserOut(BaseModel):
    id: int
    email: EmailStr
    class Config:
        from_attributes = True

JWT Auth (High Level)

Use short-lived access tokens and hashed passwords.

# app/auth.py
from passlib.context import CryptContext
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

def hash_password(pw: str) -> str:
    return pwd_context.hash(pw)

def verify_password(pw: str, hashed: str) -> bool:
    return pwd_context.verify(pw, hashed)

Routes and Docs

FastAPI automatically generates interactive docs at /docs and OpenAPI JSON at /openapi.json. That alone is a massive productivity boost for teams.

Production Notes

• Use Postgres, not SQLite, for real workloads
• Use Alembic for migrations
• Put secrets in environment variables
• Add rate limiting and request logging

This is a crash course, not a full book. But if you build this small API and deploy it, you’ll understand 80% of what you need to ship real FastAPI services.