This paper presents the design and implementation of a cloud-based communication software architecture, tailored for educational institutions. The system, RafBook-Backend, provides a unified platform for messaging, voice communication, user administration, and media sharing. Implemented in Java 17 using the Spring Boot framework, the solution integrates real-time communication technologies such as WebSocket, Firebase Cloud Messaging, and WebRTC for peer-to-peer audio channels. Data persistence is ensured with PostgreSQL, while Redis supports caching for performance optimization. The application is containerized with Docker, supported by GitHub Actions for CI/CD automation. System monitoring and logging rely on Prometheus, Grafana, and OpenSearch. The goal of this work is to provide a robust, scalable, and open-source communication tool that educational institutions can locally host and easily adapt to their specific needs.