Open a circuit
Pick one of 31 examples, or draw your own.
Power electronics simulation
Simulate a switching converter in your browser.
Open an example or draw your own converter, press Run, and read the waveforms. Free, nothing to install, no account.
Free, no accountNo sign-up, and no caps on runs or session
time.
Circuits stay putThe simulator runs in your browser. Your
circuit is never uploaded.
Portable workSave projects, share a link, export a netlist or
an image.
Three steps
Run it
Change a value and press Run. The buck example simulates 1,200 switching periods in under half a second.*
Read the waveforms
Plot any voltage or current, place two cursors, and read average, RMS, minimum, maximum and peak-to-peak.
* 0.25 to 0.42 s per run, measured in Chromium 152 on an Apple M3 Mac, October 2026.
Check it on the back of an envelope
The buck example: 5 V in, 18% duty, 2 MHz, 10 µH, 1 Ω load. The switch (or diode) and the inductor have 10 mΩ each and the trace 1 mΩ, so the load current sees 21 mΩ.
| Quantity | By hand | PWMSim |
|---|---|---|
| Output voltage | D × Vin − I × R = 0.18 × 5 V − 0.9 A × 21 mΩ = 0.881 V | 0.881 V |
| Load current | Vout ÷ R = 0.881 V ÷ 1 Ω = 0.881 A | 0.881 A |
| Inductor ripple | (Vin − Vout) × D ÷ (L × f) = 4.12 V × 0.18 ÷ (10 µH × 2 MHz) = 37 mA | 36.9 mA |
What you can do
- SimulateTransient runs of switching converters: switches, diodes, MOSFETs, IGBTs, thyristors, coupled inductors, saturable inductors, and built-in PWM, peak-current and PI controllers.
- MeasureProbes, math such as
v(out)*i(L1), cursors, measurements and a spectrum. - Open LTspice filesAn LTspice schematic opens as it was drawn and runs in the browser. See one beside LTspice.
- KeepProjects save in your browser. Share a link, or export a project file, netlist or schematic image.
What it does not do yet
- AnalysesPeriodic steady state, parameter sweeps and frequency response are not in the app yet.
- ControlNo built-in controller for line-cycle PFC or for motor drives. The motor models are experimental.
Need batch runs or CI?
Not available yet. Tell us what you need.