# PDF转换器 vs AI Audiobook Reader

The clearest difference is update cadence: AI Audiobook Reader at every 9 days against PDF转换器's every 3 weeks. PDF转换器's advantage is iOS requirement (12.4 vs 18.0). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. PDF转换器 sells 3 in-app purchases, starting at $2.99 per month and AI Audiobook Reader sells 2 in-app purchases, starting at $9.99 per month. Whichever you choose, the download price is not the number that matters.

PDF转换器 ships an update every 3 weeks, AI Audiobook Reader every 9 days. The most recent releases landed on October 14, 2026 and October 28, 2026 respectively.

## The numbers

| Metric | PDF转换器 | AI Audiobook Reader |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 3 weeks | **Every 9 days** |
| Size | 17 MB | 29 MB |
| Requires iOS | **12.4** | 18.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 12+ |
| Developer | [Shanghai Hongtai Trading Co., Ltd.](https://appshunter.io/developer/1634567281) | [SlothEase](https://appshunter.io/developer/1816632091) |

## What reviewers say

### PDF转换器

[App page](https://appshunter.io/ios/app/pdf-pdf/id6469493796)

**Features:** macOS Compatibility

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| PDF转换器-各种文档格式互转月会员 | $2.99 | per month |
| PDF转换器-各种文档格式互转年会员 | $24.99 | per year |
| PDF转换器-各种文档格式互转永久会员 | $39.99 | one-time |


### AI Audiobook Reader

[App page](https://appshunter.io/ios/app/ai-audiobook-reader-castly/id6768542554)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Castly Pro Monthly | $9.99 | per month |
| Castly Pro Annual | $49.99 | per year |


## Frequently asked questions

### Is PDF转换器 free?

PDF转换器 is free to download, with in-app purchases available.

### Is AI Audiobook Reader free?

AI Audiobook Reader is free to download, with in-app purchases available.

### Do PDF转换器 or AI Audiobook Reader have ads?

Neither PDF转换器 nor AI Audiobook Reader shows ads.

### Which is updated more often, PDF转换器 or AI Audiobook Reader?

PDF转换器 ships an update every 3 weeks, and AI Audiobook Reader every 9 days. Most recently, PDF转换器 was updated on October 14, 2026 and AI Audiobook Reader on October 28, 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.*