Several secondary metabolites, such as commonly used antibiotics, pigments and detoxifying enzymes, are synthesized by non-ribosomal peptide synthetases (NRPSs). These enzymes beautifully reflect one of the fundamental principles of synthetic biology, as they are remarkably modular. We will assemble new NRPSs by combining individual domains and modules of different origin, thus setting the basis for novel and customized synthesis of non-ribosomal peptidesTo make the use of NRPSs amenable to a wider community, we will devise a new software-tool, called NRPS Designer, which predicts the optimal modular composition of synthetic NRPSs for production of any desired peptide and outputs a cloning.