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

How to Structure Your FastAPI Projects (The Right Way)

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

Photo by Med Badr Chemmaoui on Unsplash

FastAPI has taken the Python web community by storm — and for good reason. It’s fast, intuitive, and perfect for building modern APIs. But as your application grows beyond a few endpoints, structuring your FastAPI project properly becomes absolutely critical.

A well-structured project is easier to maintain, scale, test, and onboard new developers 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…