# GTK - Circle Of Fifths — A GTK Tool

> A GTK Tool (iPhone/iPad app by Jon Machtynger.)

- Source: https://appshunter.io/ios/app/gtk-circle-of-fifths/id6757976064 (this page in markdown: same URL + `.md`)
- Developer: [Jon Machtynger](https://appshunter.io/developer/1830842869)
- Category: Music, Education
- Price: $0.99 (on sale, was $1.99)
- Age rating: 4+
- Requires: iOS 18.6 · 2 MB
- Languages: American English
- Released: 2026-01-20
- Data updated: 2026-08-24
- User reviews in markdown: https://appshunter.io/ios/app/gtk-circle-of-fifths/id6757976064/reviews.md

## What is GTK?

This app provides a comprehensive Circle of Fifths experience to help visualise one of music theory's most fundamental concepts.  It allows musicians to explore key relationships, chord progressions, and modal harmony through an intuitive and visually engaging interface.

This is one of the many tools within the comprehensive GTK Guitar Toolkit.

1) Interactive Circle visualisation
  - Press anywhere to move the circle to the primary key of your choice

2) Musical Modes and Keys
  - 7 Musical Modes: Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, Locrian
  - 12 Tonic Keys with enharmonic equivalents (C#/Db, D#/Eb, etc.)
  - Key Signature Display showing sharps/flats in the centre circle
  - Accidentals ring showing the number of sharps or flats for each key

3) Diatonic Chord Table:
  - Shows all chords in the selected key and mode
  - Chord Note Spellings displaying the actual notes for each chord
  - Roman Numeral Analysis
  - Parent Ionian Key identification for any mode

## Chart rankings

- #183 in Top Paid · Music (US App Store)


## Version history (last 1 release)

### 1.1 — 2026-01-20

No release notes.

## More apps by Jon Machtynger

- [GTK - Guitar Player's Toolkit](https://appshunter.io/ios/app/gtk-guitar-players-toolkit/id6749509640)
- [GTK - Songbook](https://appshunter.io/ios/app/gtk-songbook/id6759207277)
- [GTK - Ukulele Player's Toolkit](https://appshunter.io/ios/app/gtk-ukulele-players-toolkit/id6785108945)
- [GTK - Banjo Player's Toolkit](https://appshunter.io/ios/app/gtk-banjo-players-toolkit/id6791771235)

All apps by Jon Machtynger: https://appshunter.io/developer/1830842869

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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 2026-08-24.*