Developed a standalone Calendar Conversion Library for the OCaml ecosystem, enabling seamless date conversions between Gregorian, Julian, French, Hebrew, and Islamic calendars. The work focused on robust date manipulation and comprehensive library development, resulting in the release of calendars.2.0.0 within the ocaml/opam-repository. By reducing external dependencies, the library broadens interoperability for multi-calendar applications and integrates smoothly with existing OCaml tooling. The project demonstrated end-to-end packaging and versioning within a single month, emphasizing careful attention to OCaml language features and ecosystem standards. This contribution addressed the need for reliable cross-calendar support in OCaml-based projects requiring diverse date handling.