Qucs-S
Free circuit simulator with a schematic GUI that drives Ngspice, Xyce or Qucsator.
Updated · AppBreakup editorial · Windows, macOS, Linux
Is Qucs-S free?
Yes, free and open source
- License:
- GPL-2.0
Checked on Qucs-S's site Oct 30, 2026
Switch from Qucs-S to
All 4
Altium DesignerPaid
KiCadOpen source
- Verified facts
- 5 of 5
- Alternatives ranked
- 4
- Approved reviews
- 0
- Visits sent from here
- 0
About Qucs-S
Qucs-S is an open-source circuit simulation program that grew out of the older Qucs project. The "S" stands for SPICE: instead of shipping its own single engine, it gives you a Qt-based schematic editor and plotting front end, then hands the actual simulation to an external kernel such as Ngspice (the recommended one), Xyce or Qucsator. You draw a circuit, place probes, pick an analysis such as DC, AC or transient, and view the results as graphs inside the same window. It is aimed at students, hobbyists and engineers who want SPICE-level simulation without a commercial licence, and it is also used as research software. It is not a PCB layout tool, so people usually pair it with something like KiCad for board design. Qucs-S is free under the GPL and runs on Linux (distro packages, AppImage and Flatpak), Windows (installer bundled with Ngspice or portable zip) and macOS through a Homebrew tap.
Best for: Students and hobbyists who want free SPICE simulation with a point-and-click schematic editor.
Pros and cons
What works
- Works with several free simulation engines from one GUI
- Windows installer comes bundled with Ngspice
- Packaged for most Linux distributions, including Flatpak
- Free and open source with regular releases
Why people leave
- Needs an external simulator backend to do anything
- No PCB layout, so board design needs a separate tool
- macOS install goes through a Homebrew tap rather than an app download
Qucs-S vs Altium Designer, Proteus Design Suite and KiCad
From each app's listing and the prices verified on its own site. A dash means we haven't verified it yet.
| Attribute | Qucs-S | Altium Designer | Proteus Design Suite | KiCad |
|---|---|---|---|---|
| Pricing | Open source | Paid | Paid | Open source |
| Verified price | — | — | — | — |
| Free plan | Free app | No | No | Free app |
| Open source | Yes | No | No | Yes |
| Self-hostable | No | No | No | No |
| Platforms | Windows, macOS, Linux | Windows | Windows | Windows, macOS, Linux |
Top Qucs-S alternatives
See all 4- 1Altium Designer76.8
Commercial suite with built-in mixed-signal simulation for teams doing professional board design.
- 2Proteus Design Suite74.4
Commercial suite that simulates microcontroller firmware alongside the analog and digital circuit, then lays out the PCB.
- 3KiCad68.8
Free and open source too, and adds PCB layout on top of Ngspice-based simulation in one suite.
- 4
EasyEDA64.8Runs in the browser with schematic, simulation and PCB tools, so nothing to install.
Why people left Qucs-S
In reviewers' own words, from reviews of the apps they moved to. These are their opinions, not ours.
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Reviews
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Qucs-S: common questions
What is Qucs-S?
Qucs-S: Free circuit simulator with a schematic GUI that drives Ngspice, Xyce or Qucsator. Best for students and hobbyists who want free SPICE simulation with a point-and-click schematic editor. Available for Windows, macOS and Linux.
Is Qucs-S free?
Yes. Qucs-S is free, open-source software.
Is Qucs-S open source?
Yes. The source code is on GitHub at ra3xdh/qucs_s.
What platforms does Qucs-S run on?
Qucs-S is available for Windows, macOS and Linux.
What are the best alternatives to Qucs-S?
The highest-ranked Qucs-S alternatives right now are Altium Designer, Proteus Design Suite and KiCad. See the full ranked list for pricing, platforms and verified facts.
Qucs-S vs Altium Designer: what's the difference?
Qucs-S is free and open source; Altium Designer is a paid product. Qucs-S is open source and Altium Designer is not. Only Qucs-S runs on macOS and Linux.