To create a new variant of an existing project, developers often copy an existing codebase and modify it. This process is called software forking. After forking software, developers often port new features or bug fixes from peer projects. Repertoire analyzes repeated work of cross-system porting among forked projects. It takes the version histories as input and identifies ported edits by comparing the content of individual patches. It also shows users the extent of ported edits, where and when the ported edits occurred, which developers ported code from peer projects, and how long it takes for patches to be ported.