FEFLOW is a software package for modeling fluid flow and transport of dissolved constituents and/or heat transport processes in the subsurface. FEFLOW is a completely integrated system from simulation engine to graphical user interface including also a public programming interface for user code.

FEFLOW contains pre- and post processing functionality and an efficient simulation engine. A user-friendly graphical interface provides easy access to the extensive modeling options.

FEFLOW has been developed by the German company WASY GmbH, which is part of DHI Group. FEFLOW  is widely recognised as the most complete software package for subsurface porous media simulation and is used by leading research institutes, universities, consulting firms and government organizations all over the world. Its scope of application ranges from simple local-scale to complex large-scale simulations.