The provision of financial services adhering to banking principles as mandated by Indonesian law is central to the operations of PT BPR Aruna Nirmaladuta. To enhance customer convenience, the institution offers pick-up services and standing instructions for fund transfers via WhatsApp. However, challenges such as data security vulnerabilities, potential fraud by marketing staff, and transaction processing delays have been identified. Addressing these concerns necessitates the development of a mobile-based standing instruction (SI) application. This application aims to enhance data security through OTP codes, minimize fraud risks, and streamline transaction processes. The system design employs Unified Modeling Language (UML) within a DevOps methodology. System testing utilized black box techniques, resulting in all functional requirements being successfully met. The application was verified to handle input validation, transaction processing, and error management effectively, ensuring that all processes functioned as intended without critical failures. Consequently, this system is anticipated to facilitate transaction processes for PT BPR Aruna Nirmaladuta, ensuring improved security and ease for customers.