ARMELSAN SoPeM is a range dependent two-dimensional sonar performance modelling tool. It is developed to predict the detection performance of a sonar system in a well-defined environment. SoPeM stands out from domestic and foreign products with its user-friendly user interface, ease of use and being a WEB-based application. The SoPeM software has been updated according to the new requirements determined for the needs of the end-user Turkish Naval Forces. The processing core, installed on the server with a WEB-based application infrastructure, provides a service that responds to more than one client at the same time. Moreover, SoPeM processing core can receive and respond to commands from any client through an http/rest. SoPeM provides performance estimation for active and passive sonar applications and will have performance prediction infrastructure for multi-static sonar applications in the future. SoPeM has both web and desktop versions on Linux and Windows operating systems. SoPeM can be delivered as an integrated tool with all sonar systems produced within ARMELSAN. Moreover, it can easily be integrated to other sonar systems. SoPeM has optional “Optimum Sensor Array Depth Calculation” capability.