The development of computer technology has been followed by welding as well, in the last 15 years. It is true for software development and it is true for hardware application. The paper gives a summary of computer technology application and mathematical modeling in welding, with a demonstration of software development and modeling activities carried out in Hungary. After some statistical data about software application in welding, this paper demonstrates the differences between handling databases, calculation software and elements of Artificial Intelligence. Some of the most important results of software development carried out at the Budapest University of Technology and Economics (BUTE) are also introduced in this paper. Mathematical modeling is a very important part of information technology development in the case of welding as well.