FEATool Multiphysics vs ngspice

FEATool Multiphysics is desktop software for engineering simulation, with tools to model and solve problems across heat transfer, mass transport, structural mechanics, fluid dynamics, and electromagnetics. Models can be built in 1D, 2D, or 3D, including axisymmetric configurations. Geometry tools support modeling and exchange in STEP, IGES, STL, and OBJ formats; meshes can be generated with built-in tools or Gmsh, Netgen, tetWild, and Triangle. FEATool connects its solvers with OpenFOAM, SU2, FEniCS, and redbKIT workflows. Interface actions map to MATLAB functions, and projects can be saved as MATLAB scripts or exported as Python scripts for FEniCS. Results can be exported to MATLAB, CSV, GMV, and VTK, or as interactive ParaView Glance and Plotly web models. It runs as a standalone app on Windows and Linux, or as a MATLAB toolbox on Windows, Linux, and Intel Mac; no standalone macOS app is available. A limited-functionality trial is offered, with full-feature trials requestable for 30 days.

ngspice is a free, open-source simulator for electric and electronic circuits described as netlists. It handles analog, digital, and mixed-signal designs, with models for active, passive, analog, and digital elements; model parameters can come from collections, manufacturers, or foundries. Its SPICE compatibility supports PSPICE or LTSPICE device model parameters and netlists for discrete circuits. For mixed-signal co-simulation, it supports Verilog blocks compiled with Verilator and, since ngspice-44, VHDL blocks using GHDL. The OSDI/OpenVAF interface connects Verilog-A compact device models without requiring programming on the ngspice side. It can also be built as a shared library or DLL for another application to control. Listed integrations include KiCad, Autodesk Fusion, and Python interfaces such as PySpice. ngspice does not include schematic entry: input is through the command line or files. The stable download page offers source archives and Windows binaries; Linux users are directed to their distributor or source compilation, and the project's own macOS release is unavailable there.