FreeFEM is a solver for partial differential equations using the finite element method, aimed at non-linear multi-physics systems in 2D and 3D. Researchers and engineers use it for problems such as fluid-structure interaction, where data must be interpolated between several meshes. It provides its own language for describing physical models, a large library of finite elements and a fast interpolation algorithm. FreeFEM is written in C++ and is delivered as downloadable software for all common platforms.
The project documentation names as lead developer a professor at the Laboratoire Jacques-Louis Lions of Sorbonne Université in France. FreeFEM is released under the LGPL-3.0 licence and runs entirely on your own computers or compute cluster, so calculations and data stay with you. Development is active: the source code received changes as recently as October 2026.