FastAPI Tutorial #3 - Build Your First API | Routing, Swagger Docs, JSON Responses [2026]
In this video, we will build our first FastAPI application and understand how FastAPI handles requests and responses behind the scenes.
We will learn how to create endpoints, work with routing, explore the automatic Swagger documentation, understand JSON responses, and see how FastAPI converts Python data types into JSON automatically.
By the end of this video, you will understand the complete flow of a request in FastAPI — from the client sending an HTTP request, to Uvicorn receiving it, FastAPI routing it to the correct function, and finally returning an HTTP response.
📌 What you will learn:
✅ Create your first FastAPI endpoints
✅ Understand FastAPI routing system
✅ Work with GET routes
✅ Explore Swagger UI automatic documentation
✅ Learn about ReDoc documentation
✅ Understand JSON responses in FastAPI
✅ Understand what happens behind the scenes when a request arrives
⏱️ Chapters:
00:00 Introduction
00:33 FastAPI Setup
01:13 Creating Your First Route
02:23 Exploring Swagger UI
03:54 Exploring ReDoc
04:45 JSON Responses
07:12 Understanding Routing
08:29 Conclusion
📚 This is part of the FastAPI Complete Tutorial Series where we learn FastAPI from beginner to advanced level.
In the next video, we will explore more HTTP methods in FastAPI and learn how to return HTML responses.
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