In this paper, we present a set of software tools for developing and validating object oriented conceptual models specified in TROLL. TROLL is a formal object-oriented language for modelling information systems on a high level of abstraction. The tools include editors, syntax and consistency checkers as well as an animator which generates executable prototypes from the models on the same level of abstraction. In this way, the model behaviour can be observed and checked against the informal user requirements. After a short introduction in some validation techniques and research questions, we describe briefly the TROLL language as well as its graphical version OMTROLL. We then explain the system architecture and show its functionalities by a simplified example of an industrial application which is called CATC (ComputerAided Testing and Certifying).