myPhysicsLab vs ngspice

myPhysicsLab is a free, open-source project with interactive physics simulations and JavaScript classes for building animated models. Simulations run in real time, and users can drag objects or change parameters such as gravity. Its library includes examples such as pendulums, springs, colliding blocks, roller coasters, billiards, and molecular models. Many simulation pages explain the mathematics behind the models. Users can customize simulations with EasyScript or JavaScript in a browser and text editor, then share a setup through a URL that embeds EasyScript. Numeric results can be retrieved through VarsHistory, JavaScript, or collision-data scripts. Downloadable versions can be used offline. The source code is available on GitHub under the Apache 2.0 License. The simulations do not specify measurement units, so values need to be used consistently within each model. Building from source requires TypeScript, esbuild, Perl, and GNU Make. The project began in 2001, and its maker is based in Seattle, Washington.

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.