# Common Charts vs Number System Trainer

The clearest difference is in-app purchases: Number System Trainer at none against Common Charts's 2. On price, update cadence, ads and device support there is nothing between them.

Both are free to download. Common Charts sells 2 in-app purchases, starting at $9.99 per month. Number System Trainer asks for nothing beyond the download.

Common Charts ships an update every 9 days, Number System Trainer weekly. The most recent releases landed on September 9, 2026 and September 14, 2026 respectively.

## The numbers

| Metric | Common Charts | Number System Trainer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (10 ratings)](https://appshunter.io/ios/app/number-system-trainer/id6786437503/reviews)** |
| Number of ratings | — | **10** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 9 days | **Weekly** |
| Monetization | — | Free with in-app purchases |
| Size | 45 MB | 10 MB |
| Requires iOS | 15.1 | **15.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Tim Morgan](https://appshunter.io/developer/1631753073) | [Brandon Oaks](https://appshunter.io/developer/6786437505) |

## What reviewers say

### Common Charts

[App page](https://appshunter.io/ios/app/common-charts/id6768880611)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Common Charts Plus Monthly | $9.99 | per month |
| Common Charts Plus Yearly | $99.99 | per year |


### Number System Trainer

[App page](https://appshunter.io/ios/app/number-system-trainer/id6786437503)

Learn and master the Nashville Number System for music. This app offers interactive modules to help musicians of all levels understand chord progressions, transpose songs, and improve their ear training. It's designed for quick learning and on-the-fly musical communication.

**Highlights:** Interactive learning modules, Chord reading and identification, Instant transposition, Ear training exercises, Visual chord shapes, Circle of 4ths & 5ths reference

**Features:** macOS Compatibility, Family Sharing

**In-app purchases:** none


## Frequently asked questions

### Is Common Charts free?

Common Charts is free to download, with in-app purchases available.

### Is Number System Trainer free?

Number System Trainer is free to download, with no in-app purchases.

### Do Common Charts or Number System Trainer have ads?

Neither Common Charts nor Number System Trainer shows ads.

### Which is updated more often, Common Charts or Number System Trainer?

Common Charts ships an update every 9 days, and Number System Trainer weekly. Most recently, Common Charts was updated on September 9, 2026 and Number System Trainer on September 14, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*