ngspice vs SimFlow

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.

SimFlow is desktop software for computational fluid dynamics, covering the workflow from mesh generation through post-processing. Simulations stay on the user's hardware, and the software runs on Windows, Linux, and macOS, including Apple Silicon. Jobs can run on a local cluster, remote server, or cloud, with HPC-grade parallel computing and no per-core or hourly charges. The full simulation engine is included in every plan. CAD imports include STL, STEP, IGES, OBJ, and BRep; results can be exported in VTK, Fluent, Tecplot, and Ensight formats. SimFlow integrates with ParaView, OpenFOAM, Docker, and Windows Subsystem for Linux. The free plan has no signup, credit-card requirement, or time limit, but is limited to 200,000 mesh nodes and one CPU. Professional costs €8,000 per year; Enterprise costs €10,000 per year. Commercial plans include a 30-day trial. Perpetual licenses are also available, with one year of maintenance and optional yearly renewals.