const envPath = path.join(process.cwd(), '.env.development.local'); const content = fs.readFileSync(envPath, 'utf-8');
Different developers on a team often run different local setups.
Sometimes you need to simulate a production build locally ( npm run build && npm run start:prod ). In that scenario, you might load .env.production . But what if you need to test a Production build with a specific local override (like a different log level or a mock payment gateway)? .env.development.local
Imagine you are integrating with a third-party service like Google Maps, Stripe, or OpenAI. Your development team shares a generic DEVELOPMENT_API_KEY in .env.development . However, that shared key is throttled or tracked. If you need to test high-volume requests on your local machine, you can place your personal premium API key in .env.development.local without affecting your teammates or the CI/CD pipeline.
Remember that CRA (React) requires REACT_APP_ , Vite requires VITE_ , and Next.js exposes all by default. Using the wrong prefix is the #1 reason environment variables appear undefined . const envPath = path
Most modern frameworks utilize a library called dotenv-flow or a similar custom mechanism to load multiple .env files in a specific order of priority. If the same variable is defined in multiple files, the file with the highest priority overrides the others.
Implementing this file in your project is straightforward. Follow these steps to set it up correctly. Step 1: Create the File But what if you need to test a
.env.development.local
"files.associations": ".env.development.local": "dotenv" , "[dotenv]": "editor.tokenColorCustomizations": [
Each developer then copies this file to create their own .env.development.local :