Mustangproject is a library and tool for a open e-invoicing standard called ZUGFeRD/Factur-X.ZUGFeRD works by embedding a XML file into a PDF, making it a hybrid (i.e. both human and machine readable) invoice. Mustangproject is both a APL licensed java library and a command line tool which allows to extract and combine PDF and XML as well as migrate from ZUGFeRD v1 to v2 public preview and count how many PDF files contain ZUGFeRD metadata.