godotenv

Loads from multiple .env files (e.g., .env.development, .env.production) for managing different deployment stages, as detailed in the precedence conventions example.

Supports loading from files, io.Reader, strings, and YAML-style content, enabling integration beyond local files, as shown with Parse and Unmarshal functions.

The autoload package reads .env on import with zero configuration, reducing boilerplate code for quick setup, mentioned in the usage section.

Includes a bin command to run other commands with environment variables loaded from .env files, useful for scripting and development workflows, as described in command mode.