CircuitSim is a browser-based circuit simulator built on a full SPICE engine compiled to WebAssembly. Schematic capture, simulation, and analysis all run in the browser, with no install and no local setup.
Schematic editor. Automatic wire routing around existing components, rotate, mirror, multi-select, undo and redo, and a full set of keyboard shortcuts. Values and parts can be changed while a simulation is running, with results updating live. A netlist editor with SPICE autocomplete is available for working at the text level.
Simulation. Seven analysis types: real-time interactive simulation, interactive operating point, DC operating point, DC sweep, AC small-signal sweep with Bode magnitude and phase, transient, and parameter sweep. Parameter sweeps run across DC operating point, transient, or AC sweep, in linear, decade, octave, or list mode. Noise, distortion, and further analyses are available through the netlist. The free tier includes five analysis types; DC sweep and parameter sweep are on paid plans.
Components. 3,000+ official components with manufacturer-specific SPICE models, added to weekly, plus a growing community-contributed set. Every official part has its own detail page with parameters and symbol. Search opens any part in one click. The Custom Component Studio supports custom parameters, dynamic symbols, and interactive behavior, and imports KiCad symbols directly.
Measurement and analysis. Results plot live as the simulation runs. Cursors give exact time and voltage readings. Signals can be stacked, overlaid for comparison, and recolored. Gain and phase plot across frequency. Data exports to CSV in one click.
Classes and teams. Group licenses with a single dashboard for managing a class or team. Private student seats require no login and collect no personal data, keeping classroom deployments FERPA- and COPPA-compliant. Owner and admin roles control membership and access. Payment by card or NET-30 invoice.
Plans. Basic is free. Standard is $2.99 per month or $30 per year. Premium is $8.99 per month or $90 per year. Group pricing is quoted separately.
