An In-App Purchases developer is responsible for implementing and managing in-app buying options in software applications, primarily on mobile platforms. The job involves designing, coding, and testing the in-app purchase features, ensuring seamless transaction experiences for users. They also handle the integration of payment gateways to facilitate monetary transactions. They work closely with UX/UI designers to ensure optimal user experience and with data analysts to monitor purchase trends and identify areas for improvement. Their role also includes ensuring the security of transactions and compliance with relevant regulations and standards.