Envalid is a Node.js library designed for validating and accessing environment variables in applications. The library ensures that programs only execute when all required environment dependencies are properly configured and available. It provides validation mechanisms to check environment variables against specified criteria before application startup. Envalid offers executable documentation functionality, allowing developers to understand the environmental requirements and dependencies their applications expect during runtime. This documentation capability helps maintain clarity about configuration needs. The library creates an immutable API for environment variables, preventing them from being modified during program execution. This immutability ensures consistent behavior and prevents unexpected changes to critical configuration values while the application is running. The tool focuses on configuration management and environmental validation for Node.js applications, helping developers maintain secure and reliable application deployments through proper environment variable handling.