Build electromagnetic scenes in your browser — wires, solenoids, magnets, charged particles — and watch the field come alive in 2D and 3D: heatmaps, iron filings, field lines, Lorentz-force trajectories. Free, no install, runs on Chromebooks. Made for AP Physics, IB, and university E&M. It's the field lab that's been in physics classrooms since 2003 — now rebuilt browser-native.