The article describes the DecisionMaster decision support system. The importance of the decision-making problem is noted, as well as the need for the development and use of software tools for decision support. The structure and architecture of the DecisionMaster system, the main stages of the wizard for describing and solving the problem of ranking alternatives are described: setting information about the criteria, forming a list of alternatives, as well as choosing and configuring supported decision-making methods (SMART, WASPAS, Taxonomy, REGIME, PROMETHEE, and ELECTRE). The ability to generalize the decision-making problem for the simultaneous use of different decision-making methods is a distinctive feature of the developed system. An example of using the developed system for the task of determining the performer responsible for the construction of a new dam is given. The possibility of using the developed system for research purposes, in commercial projects, as well as in the educational process is noted.