The paper presents the extendable C/C++ whole-program call-graph tool MetaCG. We introduce its graph library, the Clang-based tool CGCollector to construct the call graph and attach meta information, and, CGValidate to check for missing edges given a particular execution. MetaCG offers extendability through its metadata function-annotation mechanism to transfer information between tools. It preserves inheritance hierarchies and can be serialized into json. We evaluate CGCollector’s ability to construct whole-program call-graphs for C/C++ code and, subsequently, present a performance profiler and a memory sanitizer that rely on MetaCG for whole-program call-graph information.