In this work a two-dimensional open source simulation code based on the finite difference method (FDM) has been developed. It is solved by means of the alternating direction implicit routine (ADI). The algorithm has been written in MATLAB language. The method improves computational performance and simulation time. In addition, this enables the creation of open-source simulation codes. A three-phase concentric HTS cable design has been chosen for the development of the code, nevertheless the model can be employed for any cable design. The results indicate an efficient, stable and powerful simulation code. During the development no numerical instabilities have been found. Besides that, the model is able to deliver quantities that are experimentally difficult to access.