# YEJING Smart vs SOS Viewer

The clearest difference is update cadence: SOS Viewer at fortnightly against YEJING Smart's every 25 months. YEJING Smart's advantage is iOS requirement (12.0 vs 15.6). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

YEJING Smart ships an update every 25 months, SOS Viewer fortnightly. The most recent releases landed on October 27, 2026 and October 15, 2026 respectively.

## The numbers

| Metric | YEJING Smart | SOS Viewer |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 25 months | **Fortnightly** |
| Size | 151 MB | 66 MB |
| Requires iOS | **12.0** | 15.6 |
| Devices | iPhone, iPod | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Suzhou Yejing Lighting Energy Saving Technology Co., Ltd](https://appshunter.io/developer/1597243002) | [Tech Tree Sdn Bhd](https://appshunter.io/developer/1756843252) |

## What reviewers say

### YEJING Smart

[App page](https://appshunter.io/ios/app/yejing-smart/id1597243000)

**Features:** macOS Compatibility

**In-app purchases:** none


### SOS Viewer

[App page](https://appshunter.io/ios/app/sos-viewer/id6742965163)

**In-app purchases:** none


## Frequently asked questions

### Is YEJING Smart free?

YEJING Smart is free to download, with no in-app purchases.

### Is SOS Viewer free?

SOS Viewer is free to download, with no in-app purchases.

### Do YEJING Smart or SOS Viewer have ads?

Neither YEJING Smart nor SOS Viewer shows ads.

### Which is updated more often, YEJING Smart or SOS Viewer?

YEJING Smart ships an update every 25 months, and SOS Viewer fortnightly. Most recently, YEJING Smart was updated on October 27, 2026 and SOS Viewer on October 15, 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.*