Ocsigen is a cutting-edge framework focused on building highly interactive web applications using advanced features of OCaml, a powerful functional programming language. With Ocsigen, developers can write both client and server parts of a web application in OCaml, allowing for seamless, unified, and efficient codebases that leverage OCaml's strong type-checking, performance, and maintainability. The framework includes tools such as Eliom, which enables the creation of multi-tier pages where the logic seamlessly runs on both the client and server sides, reducing the need for duplicating code for each environment. Ocsigen also provides Js_of_ocaml, a compiler from OCaml to JavaScript, enabling the execution of OCaml code in the web browser, thus fully integrating with modern web technology stacks. This approach not only optimizes development time but also enhances the reliability and security of web applications.