Express 4

Express 4 is the minimalist, unopinionated web framework that serves as the industry standard for building Node.js applications and APIs.

This release streamlined the framework by decoupling built-in middleware (excluding express.static) to maintain a lean, high-performance core. It introduced the express.Router class: a powerful tool for creating modular, mountable route handlers that simplify complex codebases. By shifting dependencies like body-parser and cookie-parser to external modules, Express 4 provides developers with granular control over their application stack. It remains the primary engine for modern web development, powering everything from simple microservices to massive enterprise platforms.

https://expressjs.com/