# ダイヤモンドZAi vs BookBank

The clearest difference is update cadence: BookBank at fortnightly against ダイヤモンドZAi's every 15 months. ダイヤモンドZAi's advantage is device support (3 vs 1) and iOS requirement (9.0 vs 26.0). On price, ads and in-app purchases there is nothing between them.

Both are free to download. ダイヤモンドZAi sells 4 in-app purchases, starting at $7.49 per month and BookBank sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

ダイヤモンドZAi ships an update every 15 months, BookBank fortnightly. The most recent releases landed on October 11, 2026 and October 21, 2026 respectively.

## The numbers

| Metric | ダイヤモンドZAi | BookBank |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | — | 96.3% of reviews |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 15 months | **Fortnightly** |
| Monetization | — | Free |
| Size | 31 MB | 63 MB |
| Requires iOS | **9.0** | 26.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [DIAMOND, Inc.](https://appshunter.io/developer/368890276) | [MINA YAMAHATA](https://appshunter.io/developer/1876322248) |

## What reviewers say

### ダイヤモンドZAi

[App page](https://appshunter.io/ios/app/zai/id527508296)

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| ダイヤモンドZAi | $7.49 | per month |
| ダイヤモンドZAi | $21.49 | per 3 months |
| ダイヤモンドZAi | $37.99 | per 6 months |
| ダイヤモンドZAi | $76.99 | per year |


### BookBank

[App page](https://appshunter.io/ios/app/bookbank-reading-tracker/id6759006906)

Track your reading habits and visualize your savings with this app. Organize books by genre, view reading statistics, and create personalized reading lists. You can also add notes to books and export your data.

**Highlights:** Organize books by account and genre, Graph view of reading savings, Passbook view of reading total, Bookshelf view with book covers, Manual book registration, Monthly log for notes, Create and share reading lists, Export book data as Markdown

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| BookBank Unlimited (Lifetime) | $59.99 | one-time |


## Frequently asked questions

### Is ダイヤモンドZAi free?

ダイヤモンドZAi is free to download, with in-app purchases available.

### Is BookBank free?

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

### Do ダイヤモンドZAi or BookBank have ads?

Neither ダイヤモンドZAi nor BookBank shows ads.

### Which is updated more often, ダイヤモンドZAi or BookBank?

ダイヤモンドZAi ships an update every 15 months, and BookBank fortnightly. Most recently, ダイヤモンドZAi was updated on October 11, 2026 and BookBank on October 21, 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.*