NumaSimBrowser-Native Electro Magnetic Transient Simulator.

Build, simulate, and analyze power electronics and power systems — right in your browser.

Get started

Browse components

Sample circuits

Schematic editor

Drag and drop component, build your single phase and/or three phase system and controls on the canvas.

Simulation engine

Run circuits in-browser using the high performance EMT solver. Watch traces stream into plots.

Multi-rate subsystems

Nest sub-circuits that run at finer time steps. Cross-rate signals flow through explicit From/GoTo labels. Cross-rate electrical connections are made possible using transmission-lines.

Observables and power flow

Name signals, scope them on the fly, and run a steady-state load-flow over the same circuit.

AI assistant

Ask the built-in chat to add components, wire them up, or explain what your circuit does.

Open file format

Circuits save as plain JSON you can read, diff, version-control, and share.

What is NumaSim?

NumaSim is web-based simlator. It combines a REACT based UI with a high-performance C++ simulation engine so you can create, simulate, and visualize results right in your browser.

This site is the user documentation:

Get started — How to start with your first circuit.
Learn — how the app works (observables, power flow, subsystems, multi-rate monitoring, wire routing, the scope panel, the chat / AI assistant) plus courses on the engineering behind EMT simulation, built around circuits you run in NumaSim.
Components — reference for every component in the palette and samples that use it.
Samples — gallery of ready-to-run example circuits. Click "Open in app" to load any sample.