This master thesis presents the component method for design of beam-to-column moment resisting conection. By dividing the connection into components and by determining characteristics of these components it is possible to determine mechanical response in sense of resistance, rotational stiffenes and rotational capacity of the connection. The procedure of evaluating the connection by its components is called component method for designing connections. The component method can be used for steel grades up to and including S460. In general it is not limited to any type of cross-section or for any kind of connection configuration. The component method is a result of many investigations across the world and is validated by tests of connections. That is the reason why the component method fairly easy allows good prediction of nonlinear behavior of moment resisting connections. The main goal of this master thesis was to develop program KMrup for calculating resistance and rotational stiffness of moment resisting connections using component method. Essentially KMrup is developed for calculating moment resisting beam to column connection with extended end plate. With adapted data input and proper reading of the results, the use of the program can be extended to use on different types of connection configurations (beam to beam, two sided beam to column connection). Software is written in web programming languages, which means that it is easy to use on practically any device that can browse the internet. KMrup requires internet browsing program The program is validated by four connection configurations that were calculated by commercial program SCIA Engineer and with results found in literature