# 小莺v4 vs Prometheus Mobile STO

The clearest difference is update cadence: 小莺v4 at every 6 days against Prometheus Mobile STO's every 3 months. Prometheus Mobile STO's advantage is iOS requirement (11.0 vs 14.0). 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.

小莺v4 ships an update every 6 days, Prometheus Mobile STO every 3 months. The most recent releases landed on September 21, 2026 and September 14, 2026 respectively.

## The numbers

| Metric | 小莺v4 | Prometheus Mobile STO |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 6 days** | Every 3 months |
| Size | 3 MB | 41 MB |
| Requires iOS | 14.0 | **11.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 17+ |
| Developer | [峰 高](https://appshunter.io/developer/1456326418) | [PROMETHEUS GROUP, INC.](https://appshunter.io/developer/1554172551) |

## What reviewers say

### 小莺v4

[App page](https://appshunter.io/ios/app/v4/id1584960586)

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

**In-app purchases:** none


### Prometheus Mobile STO

[App page](https://appshunter.io/ios/app/prometheus-mobile-sto/id6452803445)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is 小莺v4 free?

小莺v4 is free to download, with no in-app purchases.

### Is Prometheus Mobile STO free?

Prometheus Mobile STO is free to download, with no in-app purchases.

### Do 小莺v4 or Prometheus Mobile STO have ads?

Neither 小莺v4 nor Prometheus Mobile STO shows ads.

### Which is updated more often, 小莺v4 or Prometheus Mobile STO?

小莺v4 ships an update every 6 days, and Prometheus Mobile STO every 3 months. Most recently, 小莺v4 was updated on September 21, 2026 and Prometheus Mobile STO on September 14, 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.*