When it is up and running, this is a web app where you sketch an analog circuit and then play it as an instrument. The simulation solves every component at every sample, and that is what makes the knobs act as real pots. Patch up a VCO, a filter and a VCA, play from a keyboard or MIDI, and swap the filter while the sound keeps going.
Under the hood it is Rust compiled to WASM running in an AudioWorklet, using modified nodal analysis with trapezoidal integration, plus Newton iteration for the nonlinear parts. There are 22 classic filters modelled down to the component, covering the MS-20, a Moog ladder, the 303, SEM, Polivoks, Wasp, Steiner-Parker and the Juno IR3109, alongside pedal models like the Tube Screamer, the Big Muff and the Uni-Vibe. The nonlinear library includes OTAs such as the CA3080 and LM13700, plus tubes, JFETs, BBD chips, vactrols and hysteresis in magnetic cores.
The standout detail for me is that the simulator is differentiable and computes exact gradients for every component value, so circuits can be fitted to a hardware recording, part values optimised or topologies searched; one preset came straight out of that search. Hook up a DC-coupled interface and there is calibrated control voltage exchange with 1 V/oct tracking. Double-clicking a macro block zooms into its editable circuit, and playable circuits can be shared by copying a link.
It is still an early beta, and more antialiasing work remains before any benefits get claimed, with the triode models due to be checked against real hardware later. That openness about what is not finished yet reads as a good sign to me.