Build Your First API in 15 Minutes with FastAPI (Yes, It’s That Fast)

Skip the boilerplate — launch your first API in minutes.

Build Your First API in 15 Minutes with FastAPI (Yes, It’s That Fast)

Tired of clunky backend frameworks? Discover how FastAPI helps you spin up powerful, production-ready APIs — fast, clean, and with minimal code.

APIs power the modern web, and whether you’re a frontend dev looking to go full-stack or a backend beginner, FastAPI is your gateway drug. This Python framework is modern, type-hint-friendly, and shockingly quick to learn. In just 15 minutes, you’ll go from zero to a running API endpoint — with automatic docs baked right in.

Let’s get started.

Prerequisites

All you need is:

Basic Python knowledge (functions, types, etc.)

Python 3.7+ installed

A terminal and a text editor (VS Code recommended)

Let’s build an API to manage a simple list of items — something like a tiny to-do list.

Step-by-Step: Your First FastAPI App

Step 1: Install FastAPI and Uvicorn

pip install fastapi uvicorn

Uvicorn is the lightning-fast ASGI server that runs your app.

Step 2: Create main.py

Let’s write a basic FastAPI app.

# main.py 
from fastapi import FastAPI 
 
app = FastAPI() 
 
@app.get("/") 
def read_root(): 
    return {"message": "Hello, FastAPI!"}

That’s it. You now have a working API.

Step 3: Run Your App

uvicorn main:app --reload

Visit http://127.0.0.1:8000 → You’ll see: {"message": "Hello, FastAPI!"}

Visit http://127.0.0.1:8000/docs → Hello, Swagger UI.

Visit http://127.0.0.1:8000/redoc → Bonus docs, courtesy of ReDoc.

FastAPI generates all this automatically.

Bonus: Add a Path with Parameters

Let’s level up by adding an endpoint that returns an item by its ID.

@app.get("/items/{item_id}") 
def read_item(item_id: int, q: str = None): 
    return {"item_id": item_id, "q": q}

Try /items/42?q=test

Output: {"item_id": 42, "q": "test"}

Notice how type hints (int) are already validating input.

Add a POST Endpoint

Let’s accept data with a POST method using Pydantic models.

from pydantic import BaseModel 
 
class Item(BaseModel): 
    name: str 
    price: float 
    is_offer: bool = None 
 
@app.post("/items/") 
def create_item(item: Item): 
    return {"received_item": item}

Now send a POST request (use Postman or curl) to /items/:

{ 
  "name": "Book", 
  "price": 12.5, 
  "is_offer": true 
}

You’ll get the same object returned — fully validated.

What Makes This Magical?

Validation is automatic (thanks to Pydantic)

OpenAPI docs are real-time

Less boilerplate, more productivity

Async support is just an async def away

Pro Tips

Use @app.put() and @app.delete() for full CRUD.

Structure larger projects with routers (from fastapi import APIRouter)

Deploy with Docker + Gunicorn for production

Want to dive deeper? Check out FastAPI’s docs — they’re some of the best in open-source.

Conclusion: You Just Built an API in 15 Minutes

FastAPI isn’t just fast in name — it’s fast to learn, fast to write, and fast to run. With auto-validation, built-in docs, and async support, it’s no wonder companies like Microsoft, Uber, and Netflix are using it in production.

If you’re building APIs in Python, FastAPI should be your default choice.

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