An LTspice alternative that runs in your browser.
Open your .asc files on any computer, simulate with nothing to install, and let an AI agent design and verify the next circuit.
Spice++ and LTspice
LTspice is a free desktop SPICE simulator from Analog Devices. Spice++ is a different choice: browser based, shareable, with an agent built in.
| Aspect | Spice++ | LTspice |
|---|---|---|
| Runs in | A web browser | A desktop application |
| Install | None | An installer |
| Price | Free simulator, paid assistant plans | Free |
| AI design agent | Yes, with measured spec checks | No |
| Share a live circuit | By link, with view, comment or edit access | By sending files |
| LTspice .asc files | Opens and saves them | Native format |
| Device models | Level 1 MOSFETs, Ebers-Moll BJTs, VDMOS and macromodels | A far larger library of vendor models and more advanced device models |
Import LTspice .asc files
- Open your .asc files
- Placement, wires, labels and directives come across. Symbols without a match arrive as labelled placeholders with a warning.
- Same directives
- Write .op, .dc, .tran, .ac, .noise and .step on the schematic as you would in LTspice.
- Save back to .asc
- Export an LTspice schematic, a SPICE netlist or an LTspice compatible .raw waveform file.
Questions
Can Spice++ open LTspice files?
Yes. It imports LTspice .asc schematics with placement kept, and exports them back. Parts that have no Spice++ equivalent arrive as labelled placeholders with a warning, never silently dropped.
Is there an online version of LTspice?
LTspice is a desktop application. Spice++ is a separate simulator that runs in the browser and reads LTspice files, so you can work from any computer without installing anything.
Is Spice++ a good LTspice alternative on a Mac?
If you want a simulator that runs in any browser on macOS with nothing to install, yes. If you depend on a vendor's LTspice model library, LTspice remains the better fit for that work.
Will my results match LTspice?
For circuits within Spice++'s device models, results are checked against closed-form answers and against ngspice, another SPICE engine. See the validation page for the reference circuits and known limits.
What does Spice++ add?
An AI agent that designs from a spec, simulates, measures each target and repairs the circuit until it passes, plus sharing by link and live collaboration.