CodeCompass is an open source LLVM/Clang-based tool developed by Ericsson Ltd. and Eötvös Loránd University, Budapest to help the understanding of large legacy software systems. Based on the LLVM/Clang compiler infrastructure, CodeCompass gives exact information on complex C/C++ language elements like overloading, inheritance, the usage of variables and types, possible uses of function pointers and virtual functions - features that various existing tools support only partially. Steensgaard’s and Andersen’s pointer analysis algorithms are used to compute and visualize the use of pointers/references. The wide range of interactive visualizations extends further than the usual class and function call diagrams; architectural, component and interface diagrams are a few of the implemented graphs. To make comprehension more extensive, CodeCompass also utilizes build information to explore the system architecture as well as version control information. CodeCompass is regularly used by hundreds of designers and developers. Having a web-based, pluginable, extensible architecture, the CodeCompass framework can be an open platform to further code comprehension, static analysis and software metrics efforts. The source code and a tutorial is publicly available on GitHub, and a live demo is also available online.