NumaSimSchematic editor
An infinite canvas for building circuits, single-phase and three-phase systems, and the controls that drive them.
Browser-native EMT simulator
Build, simulate, and analyze circuits, power systems and power electronics right in your browser.
NumaSim brings professional-grade simulation to the web. No install, no license server. Any device, any OS, any browser.
Everything in one tab
A complete simulator
From a simple circuit to a three-phase network with controls — author it, run it, and analyze the waveforms without leaving the browser.
Simulation engine
Run circuits locally with a high-performance EMT solver. Watch traces stream into plots as the simulation ticks.
Multi-rate subsystems
Nest sub-circuits that run at finer time steps.
Power flow
Run a steady-state load-flow to initialize a transient study.
AI assistant (Coming soon)
Ask the built-in chat to add components, wire them up, or explain what your circuit is actually doing.
What you can build
One canvas for all domains
Mix control, circuits, power electronics, and power systems in a single model — then probe any signal and run.
01
Control systems
Block diagrams, feedback loops, PID, and digital logic. Design and tune controllers alongside the plant they drive.
Browse control blocks →02
Circuit simulation
Full electromagnetic-transient waveforms from R/L/C networks: switching ripple, inrush, and fault transients, microsecond by microsecond.
How EMT works →03
Power electronics
Switch-mode converters, rectifiers, and inverters with diodes and IGBTs. See the real switched waveform, not just the average model.
Open a converter sample →04
Power systems
Three-phase networks, transformers, and transmission lines. Run a steady-state power flow and a full EMT study over the same diagram.
How power flow works →Plans
Free to run. Free to start building.
Opening and running any circuit is free for everyone — no account. A free account lets you create and edit circuits.
Free
- Open and run any circuit — no sign-up
- Create and edit with a free account
- Full component library and samples
ProComing soon
- Everything in Free
- No circuit-size cap
- Larger models and studies
See Plans & limits for the full breakdown of free-tier caps and what Pro will unlock.
Accounts & your data
Sign in is optional — and we ask for as little as possible
You can open and run any circuit without an account. Signing in is only needed to create and save your own work — and when you do, we request just the basics.
Use it without signing in
Open any sample or shared circuit and run a full simulation anonymously. No account, no sign-up, and nothing about you is collected.
What an account unlocks
A free account lets you create, edit, and save your own circuits and manage your plan. You can sign in with Google, or with an email and password.
For the full details, see our Privacy Policy and Terms of Service.