An Apache Cordova developer designs and creates mobile applications using the Apache Cordova framework. This involves using HTML, CSS, and JavaScript to develop cross-platform apps that can run on various mobile operating systems like iOS, Android, and Windows. The developer is responsible for designing the application's interface, integrating back-end services, and testing the app's functionality. They also manage any updates or changes to the app post-release. Additionally, they ensure the app's compatibility with different devices and resolve any issues or bugs that arise. They may also work on enhancing the app's performance and user experience.