The article explores in detail the methodologies for developing web applications for medical clinics using the popular React library. The main goal of this study is the analysis of modern approaches to the creation of web applications that meet the specific requirements of medical institutions. Particular attention is paid to the functional and non-functional characteristics that are critical to such systems, including data security, user experience, integration with existing systems, and compliance with regulatory standards. First of all, a comprehensive analysis of the requirements of medical clinics for web applications was carried out. Data security is one of the most important aspects as healthcare institutions work with sensitive information. The study examines methods for ensuring the confidentiality and integrity of medical data, including compliance with HIPAA and GDPR standards. React makes it easy to integrate modern security tools such as JWT (JSON Web Tokens) for authentication and authorization, and use secure HTTP connections for data transfer. In addition, special attention is paid to the user experience (UX/UI), which should ensure the convenience and efficiency of using the web application by both medical personnel and patients. React allows you to create dynamic and interactive interfaces that can adapt to different devices and screens, thus providing a high-quality user experience. This is especially important for medical applications, where the accuracy and speed of interaction can affect the quality of healthcare delivery. A detailed description of best practices and approaches to web application development using React is provided. A component architecture is considered, which provides modularity and code reuse, which is a key factor in creating scalable and easily maintainable applications. Different methods of state management in the application, such as the use of Context API and Redux, have been explored, which allows for efficient data management and stable operation of the application. Guidelines for configuring routing using the React Router library are described, allowing you to create dynamic and multi-page applications while providing smooth navigation and a good user experience. In addition, ways to ensure application security are considered, including protection against XSS attacks, CSRF and other types of vulnerabilities, which is critical in medical applications. The article provides specific recommendations for implementing a web application for a medical clinic. They include practical code examples that demonstrate the implementation of key functionalities such as user registration and authentication, medical record processing, and database interaction. The process of setting up the infrastructure for development, testing and deployment of the application is described, including the use of CI/CD tools to automate these processes, which contributes to increasing the efficiency of development and the quality of the final product. The article provides valuable information for developers who seek to create effective and secure web applications for medical clinics using modern technologies. The conclusions and recommendations presented in the study will help ensure high quality and compliance of the developed solutions with modern industry standards and requirements, which will contribute to increasing the efficiency of the work of medical institutions and the quality of medical services provided to patients