The following paper presents a freeware modelling tool simulating dynamic systems that can be represented by either an ordinary differential equation (ODE) or a set of differential equations of different orders. The main idea leading to this software development is related to the fact that many physical, biological, ecological, economical, chemical, social and engineering problems can be expressed in this way. Furthermore, the solution to these problems requires some expertise in numerical methods and programming. Such knowledge is uncommon in some of the experts in such scientific domains. A tool to fill in this knowledge gap, increase productivity within modelling-related research and support the teaching of mathematical modelling topics is thus needed. This paper introduces System Solver, a computer application that facilitates the formulation of initial value problems for ODE systems, numerically solves these problems and provides a user with not only the solution but also debugged Visual Basic source code for the application. The obtained code can be easily shared among researchers, which facilitates the replication of numerical experiments even across different operating systems. This software's introduction is accompanied by examples from different domains, including one example from stochastic modelling.