DuMux, DUNE for Multi-{Phase, Component, Scale, Physics, ...} flow and transport in porous media, is a free and open-source simulator for flow and transport processes in porous media. It is based on the Distributed and Unified Numerics Environment DUNE. Its main intention is to provide a sustainable and consistent framework for the implementation and application of porous media model concepts and constitutive relations. It has been successfully applied to CO2 storage scenarios, environmental remediation problems, transport of therapeutic agents through biological tissue, and subsurface-atmosphere coupling. The development of DuMux started in January 2007 at the University of Stuttgart. DuMux comes in form of an additional DUNE module and inherits functionality from the DUNE core modules and from the discretization module dune-pdelab. DuMux is associated partner of the OPM (Open Porous Media) initiative.