Worked on the iOfficeAI/AionUi repository to deliver full Spanish (es-ES) localization across both desktop and renderer services, making Spanish available as a selectable language in settings and login. Leveraged React and TypeScript to implement locale registration, update language normalization logic, and integrate comprehensive es-ES translations throughout core UI modules. Enhanced the internationalization (i18n) infrastructure by updating tests, addressing formatting and fallback behaviors, and ensuring reliable localization. This work expanded the application’s accessibility for Spanish-speaking users and established a scalable foundation for future locales, demonstrating a focused approach to frontend development and internationalization within a modern JavaScript framework.