Jacob (JAva COde Builder) is a general-purpose code generator. It focuses on simplicity, ease of use and high extensibility. It is implemented in Java and uses plain Java source files as the input model. Using the Java compiler API, Jacob provides access to all model elements including packages, classes, methodes, fields and annotations. Currently three rendering engines are supported: Velocity, StringTemplates and FreeMarker, but Jacob may easily be extended with additional ones.