SPICE Netlist Simulator Online
Cloud3 free/daySimulate SPICE netlists online (op/tran/ac) with ngspice — no install, free daily allowance. In-page AC and transient waveforms, DC node voltages, full log.
Sample netlist: RC low-pass (copy into a .cir file)
* SPICE — RC low-pass filter (R1 = 1kΩ, C1 = 100nF) * Pick the analysis above (op / tran / ac) — this deck has no control block, * so the page parameters are used (e.g. tran step 1u stop 1m, or ac 1..1e6). V1 in 0 DC 5 AC 1 R1 in out 1k C1 out 0 100n .end
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This tool runs on Vecaria's processing service and requires an account. Sign in and you'll return to this page to continue.
Sign inDrag files here, or click to browse
Supports CIR, SP, NET, CKT
Choose fileSign-in required; cloud tasks draw from your cloud credits by weight (see pricing for free/Pro rules).
After submission this page polls the job every 2 seconds for up to about 11 minutes; if it times out, please resubmit (the server allows up to 10 minutes per job).
Drawing digital timing waveforms? Use Timing Waveform — browser-local, no sign-in needed.
What is it? SPICE Netlist Simulator Online runs netlist-file SPICE simulations (op/tran/ac) on our servers with ngspice and returns the results in-page — AC magnitude/phase curves, transient series, and the DC operating point as a node-voltage table — plus the full ngspice log you can download. Bring a .cir/.sp/.net/.ckt netlist or copy the built-in RC low-pass sample; no local install required. Failed runs (a .control block with no analysis command, a mistyped command, a non-positive AC points value) fail loudly with the log tail attached. Common PSpice/LTspice model cards are supported; vendor-proprietary models may not be. Sign-in required; counts against your cloud quota.
TL;DR: Simulate a SPICE netlist online (op/tran/ac) with ngspice — in-page waveforms, DC node voltages and the full log, no local install.
How to use
- Sign in, then choose a SPICE netlist file (.cir/.sp/.net/.ckt) — or copy the built-in RC low-pass sample netlist (shown in-page) into a .cir file to try one without writing anything.
- Pick the analysis (op/tran/ac) and set its parameters — SPICE notation like 1u or 1e6.
- Click "Process in cloud" and wait for the job (this can take up to about 10 minutes).
- Inspect the in-page waveforms (AC magnitude/phase, transient series) or the DC node-voltage table, expand the log summary, then download the full result log.
FAQ
Which analyses are supported?
Operating point (op), transient (tran) and AC sweeps are supported.
What does the page show after a run?
AC sweeps are plotted per node as magnitude and phase curves (log x-axis), transients as time series, and the DC operating point as a node-voltage table. In-page plots are a decimated preview — exact values live in the downloadable log. Failed runs fail loudly with the log tail attached.
When are files deleted?
Cloud task inputs, results and download links are deleted 24 hours after the task completes (see the privacy note).
Do I need to install ngspice or LTspice?
No — the simulation runs on our servers with ngspice. You only need a netlist file (.cir/.sp/.net/.ckt) and an account; the results come back as in-page plots plus a downloadable log.
Can I use my PSpice or LTspice model cards?
Common PSpice/LTspice-style model cards are supported. Vendor-proprietary models may not run — if one fails, the run fails loudly with the log tail attached so you can see exactly why.
What does it cost? Why is a sign-in required?
Simulation happens on our servers (not in your browser), so runs require an account and draw on your cloud quota. The free daily allowance covers everyday netlists; see the pricing page for the quota details.
Examples
- Upload a .cir netlist → pick ac/tran → inspect the in-page waveforms → download the full log
- No netlist handy? Copy the in-page RC low-pass sample into a .cir file and run it
Supported formats
Limitations
- Requires an account; cloud tasks count against your cloud quota.
- Runs on ngspice (BSD-3). Common PSpice/LTspice-style model cards are supported; vendor-proprietary models may not be available.
- If the netlist carries its own .control block, the page parameters are ignored — the netlist's own control commands take precedence.
- Returns the raw ngspice output log (print all is appended only when the netlist has no .control block).
- In-page plots are a decimated preview (up to 2000 points per series and up to 6 plots, decimated uniformly and disclosed when capped) — exact values are in the downloaded log.
- Failed runs (e.g. a .control block without an analysis command, a mistyped command, or a non-positive AC points value) raise an explicit error with the log tail attached instead of returning a truncated log.
Privacy
This tool has no local processing path: your file is uploaded over an encrypted connection to our own VPS, used only for this job, stored for 1 days by default and auto-deleted — or delete it earlier at any time.