🚀 What is FastAPI?

FastAPI is a modern Python web framework used to build APIs (Application Programming Interfaces) quickly and efficiently.

It is especially popular for building:

• REST APIs
• Backend services
• Microservices
• Backend for web & mobile apps

FastAPI is built on top of:

• Starlette → for web handling (requests, responses, middleware)
• Pydantic → for data validation using Python type hints

🤔 Why is it called FastAPI?

Because it is fast in two ways:

1. Fast performance
   • One of the fastest Python frameworks
   • Comparable to Node.js and Go
   • Uses async features (async / await)
2. Fast to develop
   • Less code
   • Automatic validation
   • Auto-generated API documentation

🧠 Why use FastAPI? (Key Benefits)

1️⃣ Easy to Learn (Pythonic)

• Uses standard Python type hints
• Clean and readable syntax
• Great for beginners moving from Flask

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def home():
    return {"message": "Hello FastAPI"}

2️⃣ Automatic Data Validation

FastAPI validates request data automatically.

from pydantic import BaseModel

class User(BaseModel):
    name: str
    age: int

If wrong data is sent:

• FastAPI returns a clear error
• You don’t write validation code manually

3️⃣ Built-in Interactive API Docs 📘

No extra tools needed!

• Swagger UI → /docs
• ReDoc → /redoc

👉 Perfect for learning and testing APIs.

4️⃣ Very High Performance ⚡

• Built using ASGI
• Supports async / await
• Handles thousands of requests efficiently

Good for:

• Real-time apps
• High traffic APIs

5️⃣ Dependency Injection (Clean Code)

FastAPI has a powerful dependency system:

• Authentication
• Database connections
• Reusable logic

Example:

from fastapi import Depends

6️⃣ Production-Ready Features

Out of the box support for:

• Authentication (JWT, OAuth2)
• Middleware
• Background tasks
• CORS
• WebSockets

🆚 FastAPI vs Flask vs Django (Quick View)

Feature	FastAPI	Flask	Django
Performance	⚡ Very Fast	Medium	Medium
Async Support	✅ Yes	❌ No (native)	⚠️ Limited
Validation	✅ Automatic	❌ Manual	⚠️ Forms
API Docs	✅ Auto	❌ No	❌ No
Learning Curve	Easy	Easy	Steep

🎯 When should you use FastAPI?

Use FastAPI if you want to:

• Build APIs (not full HTML websites)
• Create microservices
• Learn modern backend development
• Build scalable & high-performance apps
• Prepare for real-world backend jobs

Keep Learning 🙂