.env File

Environment variables

In one sentenceA private settings file that holds an app's secrets (API keys, passwords, database addresses) separately from the code.

What it means

Instead of typing an API Key directly into the code, apps read it from an environment variable, usually stored in a file named .env. The code can then be shared or published while the secrets stay on your machine or server.

How to use it

• Never upload a .env file to GitHub, a website, a shared drive or an AI chat. Add it to .gitignore so Git skips it.
• If a .env file leaks, change every key in it right away.
• When an AI agent builds you an app, ask it to put all secrets in a .env file and give you a .env.example with the names but not the values.

Related terms

API Key Git & GitHub VPS / Server AI Data Privacy