A precision tuner: half-folded, the tuner sits above the fold and the keyboard below
Does Fine Tuna work on iPhone Duo?
Yes, from launch day, says its developer: closed it's a focused tuner, open you can browse temperaments side by side, and half-folded the keyboard snaps to the hinge below the tuner.
- App Store confirmedJeffrey Grossman, the developer, in a submission to FoldHunt on October 18, 2026. The release notes for version 1.3 (released October 22, 2026) say "iPhone Duo Support." The description does not mention the Duo.
Adapted for the fold
- Closed · Outer display
A focused tuner
On the cover, Fine Tuna is a focused tuner, with an optional small keyboard.
- Book · Partly folded
Tuner above, keys below
Half-folded, the tuner sits above and the keyboard snaps to the hinge below it.
About Fine Tuna
Fine Tuna is a precision tuner for musicians who care about the details, especially early-music players who need to know exactly what a temperament is doing. It’s by harpsichordist and conductor Jeffrey Grossman. Pitch detection stays readable through fast attacks, noise and overtones, and there are 16 tuner views, 40 built-in temperaments or your own, a Temperament Explorer to see and hear them, and a keyboard with 13 sounds. It’s free, with a Pro upgrade.
On the iPhone Duo, the developer says the cover is a focused tuner with an optional small keyboard, and the open display lets you browse temperaments side by side. Half-folded, the tuner sits above and the keyboard snaps to the hinge below it.
Evidence reviews
What we checked, when, and what the evidence establishes. Each record preserves the support label at that check.
· App Store page reviewed
App Store confirmed · iphone-duo
The App Store release notes for version 1.3 (released October 22, 2026) mention iPhone Duo: "iPhone Duo Support."
App version: 1.3.
Store text only: we haven't seen the app running, and the store page doesn't show how each pose is used.
View reviewed evidence ↗
Related guides
iPhone Duo poses: closed, open, book, standing and Split View
A plain-language guide to the ways you will hold iPhone Duo, what the phone itself does in each, and the apps and ideas that make the most of them. For anyone buying one, and for anyone building for it.
The best iPhone Duo apps so far (October 2026)
The apps worth installing now that iPhone Duo is on sale, from the apps Apple named as launch partners to indie apps whose developers have shown a real iPhone Duo layout, picked for what they do when you open the phone.
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Every iPhone app opens on iPhone Duo, but only updated ones fill the inner display. What an app looks like before its developer adapts it, how to tell which are ready, and which popular apps have said so.
Is this your app?
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Sources: Fine Tuna on the App Store (apps.apple.com) · Fine Tuna's site (finetuna.app)
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