# BLACK JACK PROBABILITY vs 読書管理CatBook

The clearest difference is ads: BLACK JACK PROBABILITY at none against 読書管理CatBook's shown. 読書管理CatBook's advantage is update cadence (monthly vs every 4 months) and iOS requirement (12.0 vs 16.0). On in-app purchases and device support there is nothing between them.

BLACK JACK PROBABILITY ships an update every 4 months, 読書管理CatBook monthly. The most recent releases landed on July 22, 2026 and June 11, 2026 respectively.

## The numbers

| Metric | BLACK JACK PROBABILITY | 読書管理CatBook |
| --- | --- | --- |
| Price | — | **Free** |
| Positive reviews | — | 75.0% of reviews |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | Every 4 months | **Monthly** |
| Monetization | — | Ad-supported |
| Size | 5 MB | 82 MB |
| Requires iOS | 16.0 | **12.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [MIAOU, KK](https://appshunter.io/developer/1547778886) | [Sumie Watanabe](https://appshunter.io/developer/1349237972) |

## What reviewers say

### BLACK JACK PROBABILITY

[App page](https://appshunter.io/ios/app/black-jack-probability/id1547778883)

**Features:** macOS Compatibility

**In-app purchases:** none


### 読書管理CatBook

[App page](https://appshunter.io/ios/app/catbook/id1565953416)

Track your reading progress, including title, author, and reading status. Organize books by series or magazine issues and get reminders for library book returns. Easily add books via ISBN scan.

**Highlights:** Record title, author, volume, notes, and reading progress, Organize books by series or magazine issues, Library mode with return date reminders, ISBN search with camera scanning, Save data to CSV, Calendar view for reading records

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is BLACK JACK PROBABILITY free?

Pricing for BLACK JACK PROBABILITY is not currently listed on the App Store.

### Is 読書管理CatBook free?

読書管理CatBook is free to download, with no in-app purchases.

### Do BLACK JACK PROBABILITY or 読書管理CatBook have ads?

読書管理CatBook shows ads; BLACK JACK PROBABILITY does not.

### Which is updated more often, BLACK JACK PROBABILITY or 読書管理CatBook?

BLACK JACK PROBABILITY ships an update every 4 months, and 読書管理CatBook monthly. Most recently, BLACK JACK PROBABILITY was updated on July 22, 2026 and 読書管理CatBook on June 11, 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.*