The Ultimate Express is a high-performance HTTP server that offers full compatibility with the Express framework, built on the uWebSockets technology. It serves as a drop-in replacement for Express.js, designed to enhance speed while maintaining the same API and functionality. This library is not a fork of Express.js but rather a re-implementation that aims to match Express's behavior through rigorous testing. To install Ultimate Express, users can simply run `npm install ultimate-express`, replacing their existing Express dependency with this new library. The performance of Ultimate Express is significantly superior to that of traditional Express, with benchmarks showing it can handle requests at rates several times higher than Express, particularly in various routing scenarios and middleware operations. Ultimate Express distinguishes itself from similar projects by optimizing routing and maintaining a familiar API. While other frameworks like hyper-express and uwebsockets-express offer similar functionalities, they often lack the seamless compatibility and performance optimizations that Ultimate Express provides. For instance, Ultimate Express can achieve routing speeds that are up to ten times faster than standard Express routes by utilizing native uWS routing capabilities. In terms of performance metrics, extensive testing has demonstrated that Ultimate Express can handle a much higher number of requests per second compared to Express, with speedups ranging from 5X to over 11X in various scenarios. Real-world applications have also shown a notable increase in requests per second, further validating the library's efficiency. While Ultimate Express aims for compatibility with Express, there are some differences to note. For example, case-sensitive routing is enabled by default, and the request body is only read for specific HTTP methods unless configured otherwise. Additionally, the setup for HTTPS differs slightly, requiring users to pass SSL options directly to the express() constructor. To maximize performance, users are encouraged to follow specific guidelines, such as avoiding the use of external middleware for static file serving and body parsing, opting instead for the built-in methods provided by Ultimate Express. The library also creates a child thread to enhance file reading performance, which can be adjusted based on the application's needs. Ultimate Express supports a wide range of middleware and view engines compatible with Express, ensuring that developers can transition smoothly without losing functionality. However, some middleware, like compression, may not work as intended. Overall, Ultimate Express presents a compelling option for developers seeking a fast, efficient, and compatible HTTP server solution that leverages the strengths of uWebSockets while retaining the familiar Express framework experience.