# 看空气监测版 vs 小牛二维码

The clearest difference is in-app purchases: 看空气监测版 at none against 小牛二维码's 3. 看空气监测版 also leads on device support. On price and iOS requirement there is nothing between them.

Both are free to download. 小牛二维码 sells 3 in-app purchases, starting at $0.99 per 7 days. 看空气监测版 asks for nothing beyond the download.

## The numbers

| Metric | 看空气监测版 | 小牛二维码 |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | — |
| Update frequency | Every 2 months | — |
| Size | 13 MB | 35 MB |
| Requires iOS | 13.0 | **12.0** |
| Devices | **iPhone, iPod** | — |
| Age rating | 4+ | 4+ |
| Developer | [Shenzhen Everbest Machinery Industry Co.,Ltd](https://appshunter.io/developer/564470332) | [Beijing Xiaoniu Kouding Technology Co., Ltd.](https://appshunter.io/developer/1733497912) |

## What reviewers say

### 看空气监测版

[App page](https://appshunter.io/ios/app/id1251838951)

**Features:** macOS Compatibility

**In-app purchases:** none


### 小牛二维码

[App page](https://appshunter.io/ios/app/id6478612032)

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Subscribe Weekly | $0.99 | per 7 days |
| Subscribe Monthly | $0.99 | per month |
| Subscribe Annually | $5.99 | per year |


## Frequently asked questions

### Is 看空气监测版 free?

看空气监测版 is free to download, with no in-app purchases.

### Is 小牛二维码 free?

小牛二维码 is free to download, with in-app purchases available.

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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.*