In this thesis an approach to visualize internal behaviour of object oriented software is developed.

The runtime information, which can be described as objects calling other objects, is displayed as a graph consisting of nodes and edges. The aim is to design an application in Java, which takes the runtime information in form of an object call graph and visualizes it as a tree and as a force directed view.

Therefore, first a data model has to be designed, holding an object call sequence. Furthermore, a discussion about graph definition languages and according tools is made. After this different graph layout algorithms are examined as well as graph displaying tools. Finally, the implementation of this visualization program deals with the combination of these three components graph data extraction, graph layout calculation and graph visualization.