FAQ & troubleshooting

The app is slow to load.

The first visit downloads the WebAssembly simulator (~2–5 MB depending on browser). Subsequent visits use the browser cache and should load in well under a second. If you've cleared cache or are on a slow connection, give it a moment.

My circuit doesn't run.

Click Run and watch the log panel (bottom-right corner). The most common reasons:

• Unwired ports. Every component port that the simulator needs must be connected. The log flags the offending cells; click a log row to highlight them on the canvas.
• Duplicate observable names. Two wires or measurements named the same thing. Rename one of them.
• Validation failure. Some components require parameters in a specific range (e.g. a positive resistance). The log says which.

The scope is empty.

You need to add at least one observable to the scope before running. Right-click a wire and pick Add to scope, or open the trace chooser and add by name.

A trace looks like a flat line.

Either the signal genuinely doesn't change, or the Y-axis is auto-fit to a huge range. Double-click the plot to auto-fit, or drop a single trace onto its own sub-plot for an independent Y range.

Save / Open doesn't work.

NumaSim uses the browser's File System Access API on supported browsers, and falls back to the standard file picker otherwise. Some browsers prompt for permission the first time. If the prompt was dismissed, look in the address bar for a denied permission.

Do I need an account to run a circuit?

No. Opening, running, and viewing any circuit is free for everyone and needs no sign-up — the engine runs locally in your browser. You only need an account to create or edit a circuit. See Plans & limits.

What's the difference between running and editing?

Running, opening, viewing, and analysis (scopes, observables, plots) are always allowed, at any circuit size. Editing — adding or moving components, drawing wires, and changing parameter values — needs a (free) account, and the size of the circuit you can build depends on your plan.

What counts toward the free size limit?

Two things, and you're "over" if you exceed either:

• Electrical nodes (51): distinct electrical connection points (nets). Wires joined together count as one node.
• Components (200): simulator parts (sources, R/L/C, control blocks, machines, …). GUI-only helpers (labels, scopes, plain measurement read-outs) and wires don't count; a three-phase part counts as one component but contributes three nodes.

The toolbar meter shows your live usage against these caps.

I opened a circuit bigger than the free limit. Why can't I edit it?

You can still run it and change parameter values — that never goes away. While a free account is over the cap, structural edits (add / delete / rewire) are paused so the circuit can't grow further. Trim the design to fit under the cap; unlimited editing is coming soon with Pro.

When can I get Pro?

Pro is coming soon. The first release ships with the Guest and Free plans only, so there's no upgrade step yet. The "Coming soon" markers in the account menu and on Plans & limits are where the paid tier will appear once it's ready.