.env.development.local [portable] -

: 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.

You are working on a team project that uses a third-party API (like Stripe or Google Maps). .env.development.local

: You and your teammate might use different local database passwords or personal API "sandbox" keys. This file lets you use your own without breaking their setup. : When working with third-party services like OpenAI,

: Using your own personal sandbox key for services like Stripe or AWS to avoid hitting team rate limits. Best Practices ENV variables in Rails 7.x - rubyonrails-talk .env.development.local

The most critical rule regarding .env.development.local is that it (e.g., Git).