How to Use Environment Variables in Python Projects (Beginner

When building real-world Python applications, managing sensitive data like API keys, database credentials, or secret tokens securely is crucial. Hardcoding these values in your code is risky—especially when working in teams or deploying to production.

That’s where environment variables come in. They help you manage configurations outside of your source code, making your projects safer, cleaner, and easier to maintain.

What Are Environment Variables?

Environment variables are key-value pairs stored outside your code, typically in your operating system or .env file. Python can read these variables at runtime, allowing you to separate secrets and configurations from your logic.

Why Use Environment Variables?

Security: Avoids exposing credentials in your codebase
Flexibility: Easily change settings for dev, test, or production environments
Portability: Share code without sharing secrets
Clean Code: Keeps your scripts simple and maintainable

Using Environment Variables in Python

Python’s built-in os module makes it easy to read environment variables.

Example:

python

Copy code

import os

api_key = os.getenv(“API_KEY”)

print(f”Using API Key: {api_key}”)

If the API_KEY variable is not set, os.getenv() will return None.

Setting Environment Variables

1. Temporarily (on the command line)

Linux/macOS:

bash

Copy code

export API_KEY=’your-secret-key’

python your_script.py

Windows (CMD):

cmd

Copy code

set API_KEY=your-secret-key

python your_script.py

2. Using a .env File with python-dotenv

Create a .env file:

ini

Copy code

API_KEY=your-secret-key

DEBUG=True

Install the python-dotenv package:

bash

Copy code

pip install python-dotenv

Load the .env file in your Python code:

python

Copy code

from dotenv import load_dotenv

import os

load_dotenv()

api_key = os.getenv(“API_KEY”)

Best Practices

Never commit .env files to Git. Add them to .gitignore
Use different values for dev, staging, and production environments
Use defaults in case environment variables are missing:

python

Copy code

debug_mode = os.getenv(“DEBUG”, “False”) == “True”

Practice Challenge

Create a .env file with:

ini

Copy code

DB_USER=admin

DB_PASS=secure123

Write Python code to read these values using dotenv.

This hands-on task will help you understand how to manage secrets the right way.

Build Smarter Projects, Safer

Using environment variables is one of the first steps toward writing secure and scalable Python applications. Whether you’re working on Flask, Django, or data pipelines—this habit will pay off in every project.

👉 Learn how to apply these skills in real-world projects at https://www.thefullstack.co.in/courses/

You also like this:

What is Backend Development? A Complete Guide for Beginners [2025]

How to Use Environment Variables in Python Projects