The browser can play any sound so why not MIDI files. To be clear, the default implementation here is that this uses a soft synth (FluidSynth) compiled to wasm

The browser can play any sound so why not MIDI files. To be clear, the default implementation here is that this uses a soft synth (FluidSynth) compiled to wasm to render MIDI to waveform data - this is not how browsers classically played MIDI through the OS sequencer. It does also support sending out MIDI data to external devices though.