.env.local.production

However, due to developer confusion or legacy configuration scripts, you will occasionally find the inverted version: .

If you mistakenly commit this file, you are committing secrets that are intended for production-like behavior —potentially including API keys that have broad permissions on your staging or live infrastructure. .env.local.production

Most modern frameworks follow a specific priority list when loading variables. If the same variable (like API_URL ) exists in multiple files, the framework chooses the "most specific" one. Generally, the order of priority looks like this: However, due to developer confusion or legacy configuration

To protect yourself:

Create React App, the older but still widely used tool, also has a specific order depending on the command executed. The Renvy package, which mimics CRA's logic, gives us a clear picture: If the same variable (like API_URL ) exists

# .env.production.local # Override the production API_URL to point to a local mock server for testing. API_URL=http://localhost:4000/mock-api

Do not rely on .env.local.production for cloud hosting platforms like Vercel, Netlify, or AWS. Cloud platforms utilize their own dashboard settings to inject environment variables securely into the runtime or build pipeline, rendering local files unnecessary on the live server. To help you implement this correctly, tell me: What are you using? (Next.js, Vite, Nuxt, etc.) Are you trying to debug a specific error with your build?