hitjam.io
A real marimba, five octaves of warm wooden bars, every one recorded.
No MIDI keyboard? Play with your computer keys: bottom rows are the lower octave, top rows the higher one. Hold Shift to sustain. ← → octave, ↑ ↓ semitone.
Marimba online
A real marimba struck with yarn mallets, one recording per bar from two octaves below middle C to two above. The long resonator tubes under the low bars are why those notes bloom and hang rather than click. And yes, the bars are wood — so are a xylophone's; the difference is size, not material.
Plug a controller in and all five octaves sit under your hands at once. On letter keys the arrow keys walk you down to the deep bars and back up again.
No download, no account, no sign-up. The bars are played by your own browser, on your own machine.