An accordion where the hinge is the bellows

It plays like the real thing

1. No movement, no soundHold a key and nothing happens until the bellows move — the air is what makes a reed speak.
2. Push and pull are different notesEvery key has one note when the bellows open and another when they close, so a scale runs back and forth with the bellows, like on a melodeon or a norteño box.
3. Pressure is toneA gentle push is soft and dark; a firm one is loud and bright. The reeds are synthesized on the phone, so the brightness follows your hands continuously.
4. Calibrated to youA short warm-up learns how far and how fast you move, and how quiet your phone's sensor is when you hold still.

Six button accordions

Every layout is on the button chart with the push and pull note of each key — you can play it in the browser.

Registers, like the switches on a real box

Clarinet and Violin are free. Pro adds Bassoon (the low reed), Bandoneón (low and middle), Musette (three reeds, one sharp and one flat, for that shimmering Paris waltz) and Master (everything at once). Bass keys have their own reeds with an octave on top, so the basses are audible even on the phone's speaker.

Share how you played

Record up to a minute and Foldeon turns it into a vertical video: the accordion stands upright, the bellows open and close the way your hands did, the pressed keys light up and the notes you play appear on top. Free videos carry a small “Played on Foldeon” mark; Pro removes it.

What it looks like

Foldeon Pro

One purchase, no subscription: five more instruments, four more registers and videos without the watermark.

Private by design

No account, no ads, no tracking. Foldeon never uses the microphone; the tilt of the phone is read on the device only to move the bellows. Recordings stay on your iPhone until you share them. Purchases are verified through RevenueCat — see the privacy policy.