# PureTune Keys — Just Intonation Keyboard

> Just Intonation Keyboard (iPhone/iPad app by Hiroto Okawa.)

- Source: https://appshunter.io/ios/app/puretune-keys/id6800927665 (this page in markdown: same URL + `.md`)
- Developer: [Hiroto Okawa](https://appshunter.io/developer/1895506822)
- Category: Music, Education
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 15.0 · 10 MB
- Languages: American English
- Released: 2026-08-29
- Data updated: 2026-09-15
- User reviews in markdown: https://appshunter.io/ios/app/puretune-keys/id6800927665/reviews.md

## What is PureTune Keys?

PureTune Keys is a keyboard for playing and comparing equal temperament and just intonation. Hear the difference in intervals and chords directly on the on-screen keyboard. A supported wired USB MIDI keyboard can also be used.

FEATURES
• Switch between equal temperament and just intonation
• Choose major or minor
• Select a root key
• Adjust the waveform, master pitch, and volume
• Sustain notes after releasing the keys
• Shift the keyboard octave
• See active notes and tuning offsets
• Stop every note instantly with the Off button

The free version includes Root C. A one-time Pro purchase permanently unlocks the other 11 root keys. This is not a subscription.

MIDI hardware is optional. Every feature can be reviewed with the on-screen keyboard.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Unlock All 12 Keys | $4.99 | one-time |



## Version history (last 1 release)

### 1.0 — 2026-08-29

No release notes.

## More apps by Hiroto Okawa

- [Ripeto（リペト）](https://appshunter.io/ios/app/ripeto/id6763823548)

All apps by Hiroto Okawa: https://appshunter.io/developer/1895506822

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-15.*