# Chess Opening Book vs YKI Master

The clearest difference is in-app purchases: YKI Master at none against Chess Opening Book's 1. Chess Opening Book's advantage is iOS requirement (15.0 vs 26.0). On price, ads and device support there is nothing between them.

Both are free to download. Chess Opening Book sells 1 in-app purchase, starting at $1.99 per month. YKI Master asks for nothing beyond the download.

## The numbers

| Metric | Chess Opening Book | YKI Master |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | — | Every 2 days |
| Size | 12 MB | 11 MB |
| Requires iOS | **15.0** | 26.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Mert Kuplulu](https://appshunter.io/developer/6809224649) | [Aturo Trips OY](https://appshunter.io/developer/1842058395) |

## What reviewers say

### Chess Opening Book

[App page](https://appshunter.io/ios/app/chess-opening-book/id6809224647)

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Black repertoire | $1.99 | per month |


### YKI Master

[App page](https://appshunter.io/ios/app/yki-master/id6814178900)

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

**In-app purchases:** none


## Frequently asked questions

### Is Chess Opening Book free?

Chess Opening Book is free to download, with in-app purchases available.

### Is YKI Master free?

YKI Master is free to download, with no in-app purchases.

### Do Chess Opening Book or YKI Master have ads?

Neither Chess Opening Book nor YKI Master shows ads.

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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.*