Is there a free 3D FEMM alternative for WPT?

Yes — AirInduct Sim is a free, browser-based, full-3D alternative to FEMM for the inductive WPT regime. FEMM is limited to 2D / axisymmetric; AirInduct delivers full 3D B and H fields with closed-form Biot–Savart.

When is FEMM still the right tool?

FEMM is excellent when an axisymmetric or planar 2D model genuinely captures the geometry — single solenoids, simple iron-core inductors, basic motor cross-sections. For 3D coil pairs, lateral misalignment and DTC pads, AirInduct is the better fit.

Do I need to install anything?

No — AirInduct runs entirely in the browser. No FEMM install, no Lua scripting, no Windows-only constraint.

AirInduct Sim

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ALTERNATIVE — FEMM

3D, NOT 2D

NO INSTALL

BROWSER-NATIVE

The 3D, browser-native FEMM alternative.

FEMM (and OpenFEMM) is a beloved free 2D magnetics solver — and limited to axisymmetric or planar 2D for inductive WPT. AirInduct Sim covers the same magnetostatic regime in full 3D, runs in your browser, and stays free.

01. · Why move from FEMM

Full 3D B and H fields — not 2D / axisymmetric.
Lateral misalignment, angular tilt and gap sweeps in seconds.
Eight WPT topology presets (Helmholtz, DTC, square, cross) out of the box.
Runs on any browser — Mac, Linux, Chromebook, iPad. No Windows install required.
Public REST API and MCP server for AI agents.

02. · Where FEMM still wins

Single-solenoid inductors, simple iron-core problems, classroom 2D demos and any case where axisymmetric or planar FEM is genuinely sufficient. AirInduct shines as soon as the geometry breaks 2D symmetry.

03. · Migration path

Sketch the coil in AirInduct using the eight built-in topology presets, sweep parameters in seconds, then export to KiCad, DXF or SPICE for the next stage.

See the full comparison matrix or try the Helmholtz simulator.

From 2D to full 3D, in your browser.

Open the simulator →Full comparison