Most FastAPI apps start as a single file… until they don’t.

Master the art of structuring FastAPI apps like a pro — whether you’re building APIs solo or scaling with a team.

Aashish Kumar

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2 hours ago

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FastAPI has swept the Python web up in storm — and for a reason. It’s fast, simple, and ideal for creating modern APIs. But when your application goes past a handful of endpoints, getting your FastAPI project properly structured is utterly essential.

An organized project is simpler to maintain, scale, test, and onboard fresh devs into. In this article, we’ll break down the ideal structure for a FastAPI project and explain why each part exists.

Whether you’re starting a new project or looking to refactor an existing one, this guide has you covered.

The Problem with a “Single File” FastAPI App

Let’s be honest — we’ve all done this:

# main.py
from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"message": "Hello, world"}

Simple. Clean. Great for…