An LPJmL-Python interface for operating LPJmL in a Python environment and coupling it with Python models, programmes or simple programming scripts. pycoupler was written with the aim of establishing the coupling of copan:CORE with LPJmL. Coupling with LPJmL is possible on an annual basis, i.e. for each year in which LPJmL is in coupling mode, the desired inputs must be passed via pycoupler. LPJmL simulates the corresponding year and returns the desired outputs at the end of the year. The coupled programme can use the output data to generate new inputs for the next year.