Using dotenv in Node.js enables secure environment variable management by loading configuration from .env files without hardcoding sensitive data in source code. As the creator of CoreUI, a widely used open-source UI library, I’ve implemented dotenv in hundreds of Node.js projects for database credentials, API keys, and deployment configurations. From my expertise, the most effective approach is using dotenv package with proper .env file structure for clean configuration management. This method provides secure credential storage while maintaining different configurations for development, testing, and production environments.