PartSim alternative: where to simulate circuits online now
PartSim was a free online circuit simulator from Aspen Labs, made in partnership with Digi-Key: you drew a schematic in the browser, ran simulations such as transient analysis, and saved your work on the site after signing in. It no longer exists. In a post dated January 4, 2023, Elektroda announced that schematics.com and partsim.com were shut down effective January 1, 2023, and partsim.com did not respond when we checked in October 2026. Saved PartSim designs went with it. If an old tutorial or course still points you to PartSim, these free online simulators cover the same ground.
Where to go instead
For analog circuits in the browser, the closest replacements are Falstad's Circuit Simulator (free, animated current), CircuitLab (SPICE-style, paid memberships), Multisim Live (free to try) and EasyEDA (free schematics and PCBs with simple simulation). For microcontroller projects, Wokwi and Tinkercad Circuits. Our online circuit simulators comparison puts them side by side. (digiwleea is an independent project, not affiliated with Aspen Labs, Digi-Key or Elektroda.)
For digital logic: digiwleea
If what you used PartSim for was logic (gates, flip-flops, counters), digiwleea is a free browser logic simulator built for that. It works at the switch level, every wire 0, 1 or floating, and you build NOT and NAND from CMOS transistors, then adders, latches, registers, RAM and an 8-bit CPU that runs a stored program, plus the assembly language behind it, through a 40+ level course where every part is checked against its truth table, with an AI tutor (Wleea). It does not simulate analog circuits, so for resistors, capacitors and waveforms in volts use one of the tools above.
| PartSim | digiwleea | |
|---|---|---|
| Status | Shut down effective January 1, 2023 | Live and updated continuously |
| Simulated | Analog circuits (schematics, transient analysis) | Digital logic at the switch level: 0, 1 and floating |
| Runs in | The browser (when it existed) | Any modern browser, nothing to install |
| Price | Was free | Free lab and Act I; Premium for the full course |
No sign-up is needed to start: open the lab and place your first transistor, or read the free theory course. The account (and the AI tutor) are optional.
More comparisons: Electronics and SPICE simulators
See for yourself: build a logic gate from transistors in the simulator, then follow the path from sand to an 8-bit CPU.
Open the digiwleea lab →Frequently asked
Is PartSim still available?
No. Elektroda announced that partsim.com and schematics.com were shut down effective January 1, 2023, and the site no longer responds.
What replaced PartSim?
No official replacement was named. For free analog simulation in the browser, Falstad's Circuit Simulator is the most direct substitute; CircuitLab, Multisim Live and EasyEDA are other online options. For digital logic, digiwleea and CircuitVerse are free in the browser.
Can I recover my PartSim designs?
Designs were saved on PartSim's servers, which were shut down with the site, so they are no longer reachable there.