Abstract
Self-care is an essential concept in health maintenance for patients with heart problems. Mobile applications have received significant attention for their efficacy in facilitating lifestyle management. This study aimed to develop a practical mobile application for Android smartphones to aid in the self-care of heart transplant recipients. Development followed the five stages of the ADDIE model (analysis, design, development, implementation, and evaluation). The developed self-care health diary application provides users with a detailed guide to information and behaviors necessary for self-care through two main components: "Health information" and "Health diary." We conducted a 5-day pilot test with six subject experts and four heart transplant recipients. The participants were unanimously satisfied with the application's content, but experienced difficulty with its functionality, such as screen display and button operation. The feedback was used to revise and update the application, leading to the development of the final version. This study and application significantly contribute to the creation of a sustainable healthcare environment for the growing number of heart transplant recipients by enabling them to perform daily self-care. In future, education and promotion are required for encouraging heart transplant recipients to use the application regularly and proactively.