The implementation of new materials such as dual phase (DP) steels, TRIP steels (Transformation Induced Plasticity Steel) and aluminium alloys or joining more complex dissimilar materials (three sheets/plates) having various thicknesses and various chemical compositions pose serious challenges in terms of resistance welding technologies. The article presents the possibilities of the professional SORPAS® software programme used for simulating and optimising resistance welding processes. This software programme assesses the weldability of materials by simulating welding processes and forecasting the final result, including the size of the weld nugget. In addition, the software enables the optimisation of welding processes, the simulation of post-weld joint properties, the assessment of weld quality in terms of microstructural transformations, hardness distribution and strength in specific load conditions as well as makes it possible to determine the field of welding parameters. Available versions of the software are designated as 2D and 3D. The latter version enables the modelling of complex phenomena, e.g. shunting or multi-projection welding.