COBRApy is a Python package designed for constraints-based modeling of metabolic networks and gene expression. It is an object-oriented framework that facilitates the representation of complex biological processes, including metabolism and gene expression. COBRApy does not require MATLAB but includes an interface to the COBRA Toolbox for MATLAB to support legacy codes. The package supports parallel processing for computationally intensive tasks and provides core functionalities such as flux balance analysis, flux variability analysis, and gene deletion studies. COBRApy is part of the openCOBRA Project, which aims to promote constraints-based research through freely available software. The package is available at http://opencobra.sourceforge.net/ and is compatible with various linear programming solvers and Python/Jython environments.COBRApy is a Python package designed for constraints-based modeling of metabolic networks and gene expression. It is an object-oriented framework that facilitates the representation of complex biological processes, including metabolism and gene expression. COBRApy does not require MATLAB but includes an interface to the COBRA Toolbox for MATLAB to support legacy codes. The package supports parallel processing for computationally intensive tasks and provides core functionalities such as flux balance analysis, flux variability analysis, and gene deletion studies. COBRApy is part of the openCOBRA Project, which aims to promote constraints-based research through freely available software. The package is available at http://opencobra.sourceforge.net/ and is compatible with various linear programming solvers and Python/Jython environments.