PureTune Keys
Just Intonation Keyboard
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
Compare equal temperament and just intonation as you play. Root C is free; unlock all 12 keys permanently with Pro.
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.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Hiroto Okawa, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Purchases
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Hiroto Okawa
- Size
- 10.9 MB
- Category
- Music
- Compatibility
Requires iOS 15.0 or later.
- iPhone
Requires iOS 15.0 or later. - iPad
Requires iPadOS 15.0 or later. - iPod touch
Requires iOS 15.0 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Unlock All 12 Keys $4.99
- Copyright
- © 2026 Hiroto Okawa