# Harmodus Piano - Pure Tuning — Just Intonation & Polyrhythms > Just Intonation & Polyrhythms (iPhone/iPad app by Jumpei Yamaguchi.) - Source: https://appshunter.io/ios/app/harmodus-piano-pure-tuning/id6786988622 (this page in markdown: same URL + `.md`) - Developer: [Jumpei Yamaguchi](https://appshunter.io/developer/6786988624) - Category: Music, Education - Price: Free with in-app purchases - Age rating: 4+ - Requires: iOS 16.0 · 147 MB - Languages: American English, Arabic, Catalan, Croatian, Czech, Danish, Dutch, Finnish, French (France), German (Germany) and 23 more - Released: 2026-07-18 - Data updated: 2026-08-08 - User reviews in markdown: https://appshunter.io/ios/app/harmodus-piano-pure-tuning/id6786988622/reviews.md ## What is Harmodus Piano? Harmodus Piano is a piano keyboard and metronome app with just intonation. JUST INTONATION • Real-time retuning: the app analyzes the chord you hold and applies pure frequency ratios to its root. • Switch between Equal, Just Major and Just Minor. • Adjustable reference pitch. CHORD DETECTION • 17 chords detected in real time from the notes you play. • Works with the on-screen keyboard and external MIDI. 18 SOUND SOURCES • Acoustic and synthesizer timbres — organ, clarinet and more, plus waveforms such as sine and sawtooth. • Damper pedal with natural resonance. METRONOME • 6-track mixer: accent, quarter, eighth, sixteenth, triplet and a custom n-tuplet. • Odd meters (5, 7, …) add a second accent automatically. • Tuplets and 2-beat n-tuplets (e.g. half-note triplets). • A/B alternating patterns, tap tempo, count-in and auto-stop. • Visible edge-flash and per-track click sounds. MORE • Touch and MIDI keyboard (Bluetooth or cable). • Transpose, sustain / latch. • 34 languages. Purchase information: Access to all features requires the separate purchase of either a monthly or annual auto-renewable subscription, or a one-time purchase. Eligible new users may be offered a 7-day free trial with either the monthly or annual plan. The one-time purchase does not auto-renew. Terms of Use (Apple Standard EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://harmoduspiano.musicatechlab.com/privacy/ ## Pricing and in-app purchases Base price: Free. **Subscriptions** | Subscription | Price | Period | | --- | --- | --- | | Monthly Plan | $0.49 | per month | | Yearly Plan | $2.99 | per year | ## Version history (last 5 releases) ### 1.04 — 2026-08-08 • Three purchase options are now available: monthly or annual auto-renewable subscriptions (eligible users receive 7 days free) or a one-time purchase. The monthly price has been updated. • New users now see the demo video, purchase options, and tutorial in that order. • Existing purchases continue to unlock the app. ### 1.03 — 2026-07-21 Bug fixes: • Fixed an iPhone display issue where the keyboard control bar could remain visible at the bottom of the screen when viewing chords in full screen. ### 1.02 — 2026-07-20 Bug fixes: • Improved metronome stability when the app is interrupted or sent to the background (notifications, AirDrop, calls, and other audio). • Fixed metronome click timing issues with tuplets and polyrhythms after such interruptions. • Further improvements to piano and metronome audio recovery after audio-session interruptions. ### 1.01 — 2026-07-19 Bug fixes and improvements: • Fixed an issue where audio could stop after another app played sound or after an interruption (notification, Siri, or a call), until the app was relaunched. • Fixed the instrument voice unexpectedly switching to a sine wave after such interruptions. • Fixed the MIDI connection icon sometimes appearing when no MIDI keyboard was connected. • The app's 34 supported languages are now listed correctly on the App Store. ### 1.0 — 2026-07-18 No release notes. --- *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 2026-08-08.*