🚀 Build a FastAPI Todo App the Right Way (Using uv)

Want to build a lightning-fast API without the Python packaging mess?

Let’s build a Todo API using FastAPI — but with a twist: we’ll use uv, the next-gen Python package manager that automates virtual environments, handles dependency resolution, and gets out of your way.

🧩 What is uv?

uv is a modern Python package manager that replaces pip and virtualenv with:

• 🚀 Ultra-fast dependency installation
• 📦 Automatic virtual environment creation
• 🧼 Cleaner project setup with zero requirements.txt

It’s built in Rust and is ideal for fast, reproducible Python workflows — perfect for APIs, CLI tools, and data apps.

🛠️ Step 1: Set Up the Project

mkdir fastapi-todo && cd fastapi-todo
uv init --app

uv add fastapi --extra standard

🧠 Step 2: Create the Todo Model in models.py

from pydantic import BaseModel

class Todo(BaseModel):
id: int
title: str
completed: bool = False

⚙️ Step 3: Build the API in main.py

from fastapi import FastAPI, HTTPException
from models import Todo

app = FastAPI()
todos = []

@app.get("/")
def home():
return {"message": "Welcome to the FastAPI Todo App"}

@app.get("/todos")
def list_todos():
return todos

@app.post("/todos", status_code=201)
def add_todo(todo: Todo):
if any(t.id == todo.id for t in todos):
raise HTTPException(status_code=400, detail="Todo with this ID already exists.")
todos.append(todo)
return todo

@app.put("/todos/{todo_id}")
def update(todo_id: int, updated: Todo):
for i, t in enumerate(todos):
if t.id == todo_id:
todos[i] = updated
return updated
raise HTTPException(status_code=404, detail="Todo not found")

@app.delete("/todos/{todo_id}")
def delete(todo_id: int):
global todos
todos = [t for t in todos if t.id != todo_id]
return {"message": "Todo deleted"}

🚀 Step 4: Run the Server

uv run fastapi dev

This spins up the app at http://127.0.0.1:8000. Try out your endpoints using the auto-generated docs at:

👉 http://127.0.0.1:8000/docs