Almost every browser Chladni demo uses the same trigonometric shortcut for a square plate. Schladni does not. It solves the actual free-plate eigenmodes using Kirchhoff–Love thin-plate theory via a Rayleigh–Ritz method, with real material properties for copper, steel, aluminium and brass, and reports a mean error of about 3.6% against published reference eigenvalues.
On top of that it runs grain physics in WebGPU compute shaders for up to roughly 1.2 million sand grains, renders through Three.js and React Three Fiber, and drives a modal synthesis audio engine locked to the plate's own resonances, so what you hear matches what you see. The live build is at schladni.vercel.app, in English and French.
It is very new, created in August 2026, with no stars and no external validation yet, and it is released under PolyForm Noncommercial 1.0.0, so commercial use needs permission. Worth testing your own plate measurements against.