Calculix is described as 'Free and open-source finite-element analysis application that uses an input format similar to Abaqus. It has an implicit and explicit solver written by Guido Dhondt and a pre- and post-processor written by Klaus Wittig' and is an app. There are nine alternatives to Calculix for Windows, Linux, Mac and MATLAB. The best Calculix alternative is FEATool Multiphysics, which is free. Other great apps like Calculix are COMSOL Multiphysics, Elmer, Code_Aster and Code_Saturne.
FEATool Multiphysics is a fully integrated physics modeling and engineering simulation environment, featuring built-in CAD and geometry tools, pre-processing and grid generation, solvers, post-processing and visualization.
COMSOL Multiphysics is an engineering, design, and finite element analysis software environment for the modeling and simulation of any physics-based system.
Elmer is an open source multiphysical simulation software mainly developed by CSC - IT Center for Science (CSC). Elmer development was started 1995 in collaboration with Finnish Universities, research institutes and industry.
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Code_Saturne solves the Navier-Stokes equations for 2D, 2D-axisymmetric and 3D flows, steady or unsteady, laminar or turbulent, incompressible or weakly dilatable, isothermal or not, with scalars transport if required.
Kratos Multiphysics (A.K.A Kratos) is a framework for building parallel multi-disciplinary simulation software. Modularity, extensibility and HPC are the main objectives. Kratos has BSD license and is written in C++ with extensive Python interface.
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Code_Aster is a free software for numerical simulation in structural mechanics. It is a general software for simulation in mechanics and calculation of structures.
Impact is an explicit Finite Element Program Suite which simulates dynamic impact events. It has a range of elements, contact handling and different material laws. Models can be created, solved and analyzed with the included pre- and postprocessor.
