Metabolic fluxes are the final endpoint of all co-operating actions in the complex cellular network of genes, transcripts, proteins and metabolites. In vivo fluxes, however, are not directly observable and have to be inferred by data from labeling experiments and the use of mathematical models. 13C-based metabolic flux analysis emerged as the state-of-the-art technique in the field of fluxomics. The high performance simulator 13CFLUX2 is a software suite of applications for the detailed quantification of intracellular (quasi) steady-state fluxes .