Environment variables (.env) for apps

Add them

App settings → Environment variables shows each variable as a key and value you can edit. Press + Add variable for a new row, type the key (e.g. DATABASE_URL) and value, then Save on that row or Save all. The bin icon removes a row. To add many at once, open Paste a .env file, paste one NAME=value per line and save. The app restarts with the new values.

Read them in code

process.env.DATABASE_URL          // Node.js
os.environ['DATABASE_URL']        # Python
System.getenv("DATABASE_URL")     // Java

Set for you

• PORT — the port your app must listen on
• HOST — 127.0.0.1
• NODE_ENV / APP_ENV — production or development (App settings → Mode)