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What is FastAPI?

5 min read Quiz at the end

FastAPI overview: ASGI, Pydantic validation, auto Swagger docs, and async-first performance.

What is FastAPI?

FastAPI is a modern, fast Python web framework for building APIs. Built on Starlette and Pydantic, it delivers exceptional performance and automatic interactive documentation.

Auto-generated Swagger UI docs at /docs
Type-safe request/response using Pydantic
Async-first (ASGI) — handles thousands of requests
Automatic validation and serialization
Dependency Injection built-in

pip install fastapi uvicorn
uvicorn main:app --reload   # http://localhost:8000
# Docs at: http://localhost:8000/docs

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Topic Quiz · 4 questions

Test your understanding before moving on

1. FastAPI is built on top of which framework?

💡 FastAPI is built on Starlette (ASGI) for the web layer and Pydantic for data validation.

2. Where does FastAPI auto-generate interactive API docs?

💡 FastAPI serves Swagger UI at /docs and ReDoc at /redoc automatically.

3. What is FastAPIs main data validation library?

💡 Pydantic handles all request/response validation using Python type hints.

4. Which server is recommended to run FastAPI?

💡 FastAPI is ASGI-based — use Uvicorn as the server.

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What is FastAPI?

What is FastAPI?

Test your understanding before moving on