# Thelonious — A pocket guide to music theory

> A pocket guide to music theory (iPhone/iPad app by Robert Natale.)

- Source: https://appshunter.io/ios/app/thelonious/id6760714389 (this page in markdown: same URL + `.md`)
- Developer: [Robert Natale](https://appshunter.io/developer/1885874591)
- Category: Music, Education
- Price: Free
- Age rating: 4+
- Requires: iOS 15.1 · 34 MB
- Languages: American English
- Released: 2026-04-01
- Data updated: 2026-07-09
- User reviews in markdown: https://appshunter.io/ios/app/thelonious/id6760714389/reviews.md

## What is Thelonious?

Thelonious is a music theory app designed to help you understand keys, chords, scales, and harmony through clear, visual layouts.

Explore major keys, review scale notes, and study diatonic chords in a format built for both learning and quick reference. Thelonious connects theory to real playing with chord progressions, guitar mode charts, and CAGED system material.

Use Thelonious to:

• Explore major keys and their scale notes
• Understand diatonic chords and key relationships
• Learn relative minor and dominant chords
• Study chord progressions and harmonic movement
• View guitar modes and CAGED chord charts

Whether you’re learning the fundamentals or deepening your understanding of harmony, Thelonious makes music theory easier to read, understand, and apply.


## Version history (last 1 release)

### 1.0 — 2026-04-01

No release notes.

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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 2026-07-09.*