The engineering agent for analog circuits.
Give it a spec. It designs the circuit, simulates it, measures every target and repairs it until it passes.
Spec in. Verified design out.
Design
From a sentence and a target: topology, component values and the analyses to prove it.
Simulate and measure
A real SPICE run, then every target measured from the result, not estimated.
Repair until it passes
When a spec misses, it finds the part that matters, changes it and checks again.
Every answer is measured.
The agent reports what the simulation shows: the target, the measured value and the margin, with the run one click away.
Automate the work around the design.
The analyses engineers put off, run in minutes and summarised in plain language.
Tolerance and corners
Monte Carlo and worst-case corners across component tolerances.
Optimization
Tunes component values to hit several targets at once.
Stability
Loop gain, phase margin and gain margin from the broken loop.
Noise and sensitivity
Where the noise comes from, and which part moves each spec.
Filter and converter design
Butterworth, Bessel and Chebyshev filters, and buck, boost and buck-boost converters, sized from your spec.
Fault injection
Open or short any part and see what the rest of the circuit does.
A real simulator underneath.
Operating point, DC, transient, AC, noise and sweeps, solved on your own computer. Draw by hand whenever you like, and open your LTspice, KiCad and SPICE files directly.
Questions
Is Spice++ free?
Yes. The simulator, every analysis, imports, exports and sharing are free with no limits, because the simulation runs on your computer. Paid plans add stronger assistant models and more assistant time.
Do I need to install anything?
No. Spice++ runs in a modern browser on macOS, Windows, Linux and ChromeOS.
Is it a real SPICE simulator?
Yes. It solves circuits with modified nodal analysis and Newton-Raphson, like SPICE, and any run can be checked against ngspice in the same tab.
Can I open my LTspice or KiCad files?
Yes. LTspice .asc, KiCad 6 and later, SPICE netlists and Falstad circuits import directly, with placement kept where the format has it.
How do I know the numbers are right?
Every reference circuit is checked against its closed-form answer and against ngspice, and the results are public on the validation page, including the cases that disagree.