: Variables here only load when the application is running in "development" mode (e.g., via npm run dev or npm start ). The Hierarchy of .env Files
: When working with third-party services like OpenAI, you can store your personal OPENAI_API_KEY here so it doesn't leak into the repository. .env.development.local
The .env.development.local file is a specialized environment variable file used to store configuration settings and sensitive information (like API keys or database credentials) specifically for a developer's during the development phase . Its primary characteristics include: : Variables here only load when the application
(Highest priority for local development) .env.local .env.development .env (Lowest priority; general defaults) .env.development.local
: Safely enable experimental features on your machine without forcing them on other developers. Best Practices Environment variables - Vercel
: It is strictly for local use and should never be committed to version control (Git).