GetFEM is an open source library based on collaborative development.It aims to offer the most flexible framework for solving potentially coupledsystems of linear and nonlinear partial differential equations with the finiteelement method. GetFEM is interfacedwith some script languages (Python, Octave, Scilab and Matlab) so that almostall of the functionalities can be used just writing scripts. It works inarbitrary dimension and allow to couple 1D, 2D and 3D problems. The strongpoints of GetFEM can be summarized as follows:  A weak form language (in terms of operators) that allows to translate quite  arbitrary weak formulations. A symbolic derivation that allows to  automatically obtain the tangent system for nonlinear problems. A compilation  of assembly terms into optimized basic instructions.  A model description that gather the variables, data and terms of a problem  and some predefined bricks representing classical models : elasticity in  small and large deformations, Helmholtz problem, scalar elliptic problem,  Dirichlet, contact and Neumann boundary conditions, incompressibility  constraint, ...  A complete separation between geometric transformation, finite element  method, integration methods and partial differential term description, which  allows to easily switch from a method to another.  A large set of predefined methods :  isoparametric/subparametric/overparametric elements, Pk on simplices of  arbitrary degree and dimension, Qk on parallelepipeds, pyramidal elements,  P1, P2 with bubble functions, Hermite elements, Argyris element, HCT and FVS,  elements with hierarchical basis (for multigrid methods for instance),  discontinuous Pk and Qk, vector elements (RT0, Nedelec) ...  A large set of predefined integration methods.  Structural mechanics terms (elasticity, contact with friction, plasticity ...)  Level-set and finite element cut by one or several level-set (Xfem)    Computation of terms between two meshes with an arbitrary transformation:  this is a very powerful tool of the generic assembly that allows to use a  parameterized transformation. The derivative of the transformation with  respect to the potential dependance in the variables is taken into account.  Possible use : contact problems, fluid-structure interaction, special  boundary conditions ...  Post-processing directly with Scilab, Octave or Matlab interfaces or with  the export of vtk or gmsh files. Many possibility to interpolate arbitrary  quantities, make slices, projections ...GetFEM can be used to construct very generic finite element codes, wherefinite element methods, integration methods and the dimension of the problemare the parameters that can be changed very easily. This allows a wide rangeof experiments. Many examples and demos are provided.GetFEM has only an experimental meshing procedure (and produces regular meshes).It is therefore often necessary to import meshes. The formats currentlysupported are GID, GMSH, EMC2 and ANSYS. Please read INSTALL and see the sitehttps://getfem.org/