Developed the Web Monetization Extensions API Specification for the WICG/webmonetization repository, enabling browser extensions to manage monetization sessions and customize user interfaces. The work focused on defining new API endpoints and documenting related events and types, which broadens the extensibility of the Web Monetization framework and improves developer onboarding. Collaborated closely with a co-author to review and finalize the specification, ensuring clarity and completeness. Maintained repository integrity by reverting unintended changes to package-lock.json, supporting deterministic builds. Utilized JavaScript and HTML for front end development and API design, with an emphasis on clear documentation and collaborative specification development.