> ## Documentation Index
> Fetch the complete documentation index at: https://python4ai.codewithsiva.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Using .env files

> The easy way to manage secrets

## What is a .env file?

A `.env` file is a simple text file that stores your environment variables. Instead of typing `export` commands, you write them once in a file.

## Basic setup

### 1. Install python-dotenv

```bash theme={null}
pip install python-dotenv
```

### 2. Create .env file

Create a file named `.env` in your project:

```
# .env
API_KEY=sk-1234567890abcdef
DATABASE_URL=sqlite:///myapp.db
DEBUG=True
```

### 3. Load in Python

```python theme={null}
from dotenv import load_dotenv
import os

# Load the .env file
load_dotenv()

# Now use your variables
api_key = os.environ.get('API_KEY')
debug = os.environ.get('DEBUG')

print(f"API Key: {api_key}")
print(f"Debug mode: {debug}")
```

That's it! Much easier than export commands.

## Critical: Add to .gitignore

<Warning>
  **Never commit .env files!** They contain secrets. Add to `.gitignore` immediately:

  ```
  # .gitignore
  .env
  .venv/
  __pycache__/
  ```
</Warning>

## Complete example

Here's a real example with an API:

```python theme={null}
# app.py
from dotenv import load_dotenv
import os
import requests

# Load environment variables
load_dotenv()

# Get API key
API_KEY = os.environ.get('OPENAI_API_KEY')

if not API_KEY:
    print("Please set OPENAI_API_KEY in .env file")
    exit(1)

# Use the API
headers = {"Authorization": f"Bearer {API_KEY}"}
# Make your API calls...
```

Your `.env` file:

```
# .env
OPENAI_API_KEY=sk-your-actual-key-here
MODEL=gpt-3.5-turbo
MAX_TOKENS=100
```

## Show others what they need

Create `.env.example` (this one you DO commit):

```
# .env.example
OPENAI_API_KEY=your-api-key-here
MODEL=gpt-3.5-turbo
MAX_TOKENS=100
```

This shows other developers what variables they need without exposing your actual keys.

## Rules for .env files

* One variable per line
* No spaces around `=`
* No quotes (unless part of the value)
* Use `#` for comments
* Always UPPERCASE names

## Common patterns

```
# API Keys
OPENAI_API_KEY=sk-...
GITHUB_TOKEN=ghp_...

# Database
DATABASE_URL=sqlite:///local.db

# Settings
DEBUG=True
PORT=8000
LOG_LEVEL=INFO
```

## Quick tips

1. **Load early**: Put `load_dotenv()` at the start of your program
2. **Use defaults**: `os.environ.get('PORT', '8000')`
3. **Check your .gitignore**: Make sure `.env` is listed
4. **Keep it simple**: Only put configuration that changes

## What's next?

You now know how to manage secrets safely! Ready for modern Python tooling?

<Card title="Modern Python" icon="rocket" href="/tools/dependencies/index">
  Next-level Python development
</Card>