In recent years, a great deal of attention has been received on the stability of electric power systems. A considerable amount of literature has been published on the stability of electric power systems. Lyapunov has defined a function which will install relationship between accumulated energy in the system and the dynamics of the system. This function is given by considering the concept of energy. If a system's energy is continuously decreasing until an equilibrium state is reached, the system is stable. If the total energy of a system is continuously decreased, the time derivative of energy function is negative definite. In this paper, we have presented a web-based interface for energy function analysis of two-machine infinite-bus power system. MATLAB Builder NE with WebFigures and ASP.NET platform has been used to design the web-based interface. Users can easily access and use interactive web-based simulation page for energy function analysis and also users can be analyzed the studied power system without constructing a candidate Lyapunov function. The estimate of stability regions (domain of attraction) are visualized for two-machine infinite-bus system with this web-based interface.