ngspice review
A capable free simulation engine for developers who can work with netlists and command files.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
ngspice is an open-source SPICE-compatible simulator for electrical and electronic circuits. It is designed for developers and engineering workflows that need a simulation engine for analog, digital, and mixed-signal designs rather than a complete schematic-design application. The project supports local use on Windows, Linux, and macOS, along with a shared-library API for application integration. Its input model centers on netlists and command files, making it a natural fit for software-led simulation workflows.
The analysis coverage is broad. ngspice supports DC operating-point and swept DC analysis, AC small-signal frequency analysis, transient time-domain analysis, pole-zero, distortion, sensitivity, and noise analyses. It also includes Monte Carlo and statistical circuit analysis, plus Verilog-A compact device models through OSDI/OpenVAF. Verilog and VHDL mixed-signal co-simulation extends its scope beyond conventional analog SPICE work, while compatibility with SPICE, PSPICE, LTSPICE, and HSPICE models can help fit existing model-based workflows.
Its ecosystem is strongest when paired with other tools. Integrations include KiCad, Verilator, GHDL, and OpenVAF, and the project recommends external schematic tools such as KiCad because ngspice has no built-in schematic entry. That boundary is central to the buying decision: choose ngspice for a free, open-source simulation core with extensive analysis and model support, especially when API integration or co-simulation matters. Choose another application if schematic capture and an integrated design environment are essential to the workflow.
ngspice pros and cons
- Where it wins
- Free and open source across Windows, macOS, Linux, and API use
- Advanced analog, digital, mixed-signal, noise, and statistical analyses
- Compatible with SPICE, PSPICE, LTSPICE, and HSPICE models
- Where it doesn't
- No built-in schematic capture or visual schematic entry
- Requires netlists and command files for design input
- No AI features and a desktop-focused deployment model
ngspice fact sheet, pricing and score →
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