# BookListViewer2 vs SOUNDSLAYER Engine

The clearest difference is in-app purchases: SOUNDSLAYER Engine at none against BookListViewer2's 1. BookListViewer2's advantage is update cadence (every 3 months vs every 8 months). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. BookListViewer2 sells 1 one-off in-app purchase. SOUNDSLAYER Engine asks for nothing beyond the download.

BookListViewer2 ships an update every 3 months, SOUNDSLAYER Engine every 8 months. The most recent releases landed on October 7, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | BookListViewer2 | SOUNDSLAYER Engine |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 3 months** | Every 8 months |
| Size | 11 MB | 63 MB |
| Requires iOS | **12.1** | 13.0 |
| Devices | iPhone, iPad, iPod | **iPhone, iPad, iPod, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [Mika Hatakeyama](https://appshunter.io/developer/445272831) | [PANASONIC ENTERTAINMENT & COMMUNICATION CO., LTD.](https://appshunter.io/developer/1668304757) |

## What reviewers say

### BookListViewer2

[App page](https://appshunter.io/ios/app/booklistviewer2/id975024899)

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 広告を消す | $0.99 | one-time |


### SOUNDSLAYER Engine

[App page](https://appshunter.io/ios/app/soundslayer-engine/id6503490203)

**In-app purchases:** none


## Frequently asked questions

### Is BookListViewer2 free?

BookListViewer2 is free to download, with in-app purchases available.

### Is SOUNDSLAYER Engine free?

SOUNDSLAYER Engine is free to download, with no in-app purchases.

### Do BookListViewer2 or SOUNDSLAYER Engine have ads?

Neither BookListViewer2 nor SOUNDSLAYER Engine shows ads.

### Which is updated more often, BookListViewer2 or SOUNDSLAYER Engine?

BookListViewer2 ships an update every 3 months, and SOUNDSLAYER Engine every 8 months. Most recently, BookListViewer2 was updated on October 7, 2026 and SOUNDSLAYER Engine on October 10, 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.*