Using C or C++ source for any user created tool used to be near impossible due to the complexity of the languages, especially for C++. The open source compiler clang <http://clang.llvm.org/> provides access to its internal data structures exposing all details of the source via a library interface. This library provides a basis for various tools like code-completion hints, static analysis, code transformations, etc. This presentation gives an introduction to create your own tool using C++ source.