Josh Campos
Josh's Blog; Data.Code.Cloud

Josh's Blog; Data.Code.Cloud

FAST API - Getting Started

FAST API - Getting Started

The new platform on the block that is reigning supreme over others.

Josh Campos's photo
Josh Campos
·Mar 25, 2022·

3 min read

Table of contents

  • Introduction
  • Environment
  • Tools
  • Python Virtual Environments
  • FastAPI Hello World Example
  • Run the FastAPI Server


This article is the start of a series on how to build an API using the FastAPI Framework.


This walkthrough will be built on macOS. However, no reason you can't follow along on Windows as well. I'll try to provide instructions for both when possible.

Code for this article can be found in the following GitHub Repo. Each folder will contain a separate project assigned to the assigned article in the series.


  • Python 3
  • macOS
  • VS Code (Editor) with the Python Extension from Microsoft

Python Virtual Environments

Navigate to a directory of your choosing to set up your new FastAPI Project. In your new directory follow the next Command Line/ Terminal scripts.

Virtual Environments are a Python best practice to keep different project modules/ libraries separate from each other. You can use the pip freeze command to add required libraries to a requirements.txt file. This allows you to re-install the required libraries for the project at a later time.

Setup in Windows

# Create Virtual Environment
python3 -m venv venv

# Change VS Code Python Interpreter to the VENV python Version

# Start Virtual Environment

# Command Prompt will show running Virtual Environment

Setup in macOS

# Create Virtual Environment
python3 -m venv venv

# Change VS Code Python Interpreter to the VENV python Version

# Start Virtual Environment
source venv/bin/activate

# Command Prompt will show running Virtual Environment

Install Packages

# Install FAST API with all dependencies for now
pip install "FastAPI[all]"

Running the setup commands should look like the following screenshot. The activated Virtual Environment is shown at the start of the terminal line venv.

Project Setup Commands.png

FastAPI Hello World Example


Create a new file named:

from fastapi import FastAPI

app = FastAPI()

async def root():
    return { "message": "Hello world" }

Run the FastAPI Server

From your terminal or integrated terminal in VS Code, run the following commands to start the API server.

# Start up the server
# First app is the app filename
# Second app is the name of the FastAPI instance in the file
# --reload is a hot reload flag for the FastAPI Server

uvicorn app:app --reload

Starting the server will show the running URL and Port.

Startup Server.png

Visit http://localhost:8000/docs to view the Swagger Documentation for the FastAPI Server. The ReDoc interface is also available by default at the following URL: http://localhost:8000/redoc.

The default endpoint in the example below / will return the Hello World payload.

Test Server.png

The articles in this series will cover further configurations regarding security, database connections, and more.

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