Vágner, Anikó SzilviaMenacy, Nadeen Adel Mohamed2026-02-122026-02-122025-10-21https://hdl.handle.net/2437/404353This thesis describes the development of a real-time chat web application using the MERN stack and Socket.io. The system allows users to register with an email, add friends, and exchange text or image messages in one-on-one chats. Authentication is handled through JWT stored in HTTP-only cookies, and images are uploaded via Cloudinary. React and TailwindCSS were used for the frontend, while Zustand manages client-side state. Performance tests confirmed message delivery in under one second for multiple concurrent users. The project concludes with plans for optimization, scalability, and improved data security.55enMERN StackSocket.ioChat ApplicationInformatics::Computer ScienceHozzáférhető a 2022 decemberi felsőoktatási törvénymódosítás értelmében.