COPASI is a modelling and simulation environment, which supports the OMEX format. Using the PyEnzyme library and a COPASI-specific thin API layer (TL_COPASI), the time course data (measured concentrations of substrate or product) are loaded into COPASI. Within COPASI, different kinetic laws are applied, kinetic parameters are estimated, and plots are generated to assess the result. The selected kinetic model and the estimated kinetic parameters are then added to the EnzymeML document (see SI 3.5).