How to Install FastAPI: Step-by-Step Guide

To install fastapi, run pip install fastapi in your terminal. For running your FastAPI app, also install an ASGI server like uvicorn with pip install uvicorn.

Syntax

Use the pip install command to add FastAPI and its server to your Python environment.

• pip install fastapi: Installs the FastAPI framework.
• pip install uvicorn: Installs Uvicorn, a server to run FastAPI apps.

bash

pip install fastapi
pip install uvicorn

Example

This example shows how to install FastAPI and Uvicorn, then create a simple app and run it.

bash and python

pip install fastapi uvicorn

# Create a file named main.py with this content:
from fastapi import FastAPI

app = FastAPI()

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

# Run the app with:
# uvicorn main:app --reload

Output

INFO:     Started server process [12345]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)

Common Pitfalls

Common mistakes when installing FastAPI include:

• Not installing uvicorn, so the app cannot run.
• Using Python versions older than 3.7, which FastAPI requires.
• Running pip install fastapi inside the wrong environment or without activating a virtual environment.

Always check your Python version with python --version and use a virtual environment.

bash

## Wrong way (missing uvicorn):
pip install fastapi

## Right way:
pip install fastapi uvicorn

Quick Reference

Summary tips for installing FastAPI:

• Use Python 3.7 or newer.
• Install both fastapi and uvicorn.
• Use a virtual environment to avoid conflicts.
• Run your app with uvicorn main:app --reload for auto-reload during development.

Key Takeaways

Install FastAPI using 'pip install fastapi' and Uvicorn with 'pip install uvicorn'.

Use Python 3.7 or higher to ensure compatibility with FastAPI.

Always run your FastAPI app with Uvicorn to serve it properly.

Use a virtual environment to keep your Python packages organized.

Run 'uvicorn main:app --reload' during development for automatic code reload.