INSPIRE emphasizes establishment of sustainable collaborations by stimulating open source software development. All project partners are involved in the development of open-source simulation software as part of their long term research and education strategy.
DUNE, the Distributed and Unified Numerics Environment is a modular toolbox for solving partial differential equations (PDEs) with grid-based methods. It supports the easy implementation of methods like Finite Elements (FE), Finite Volumes (FV), and also Finite Differences (FD). DUNE ensures efficiency in scientific computations and supports high-performance computing applications. DUNE is a free software licensed under the GPL (version 2).
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 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. 
OPM coordinates collaborative software development, maintains and distributes open-source software and open data sets, and seeks to ensure that these are available under a free license in a long-term perspective. Current development is focused on CO2 sequestration and improved and enhanced oil recovery. For instance, the Flow software is a reservoir simulator for three-phase black-oil problems using a fully-implicit formulation. There are also specialized variants for solvent and polymer problems. 

The code ComPASS is an open source code initiated by UCA-LJAD-Inria and BRGM (french Geological Survey) in 2015. It is devoted to the simulation of multiphase non-isothermal Darcy flows and includes complex network of fractures/faults represented as interfaces of co-dimension one coupled to the surrounding matrix. The discretization is based mainly on vertex and fracture face unknowns and is adapted to polyhedral meshes and heterogeneous media. The ComPASS code is co-developed since 2017 by the partners of the ANR CHARMS project including BGRM, LJAD-Inria, Storengy, la Maison de la Simulation and the Jacques Louis Lions laboratory. The main objective of the CHARMS project is to develop a new generation flow simulation tool for geothermal systems focusing on fluids and accounting for complex fault networks and wells.