# Shadow Echo vs 海龜湯 · AI 深夜推理

The clearest difference is in-app purchases: Shadow Echo at none against 海龜湯 · AI 深夜推理's 3. Shadow Echo also leads on update cadence (every 3 days vs fortnightly). 海龜湯 · AI 深夜推理's advantage is ads (none vs shown). On price, device support and iOS requirement there is nothing between them.

Both are free to download. 海龜湯 · AI 深夜推理 sells 3 one-off in-app purchases. Shadow Echo asks for nothing beyond the download.

Shadow Echo ships an update every 3 days, 海龜湯 · AI 深夜推理 fortnightly. The most recent releases landed on October 31, 2026 and November 6, 2026 respectively.

## The numbers

| Metric | Shadow Echo | 海龜湯 · AI 深夜推理 |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | **Every 3 days** | Fortnightly |
| Size | 22 MB | 108 MB |
| Requires iOS | 16.0 | **15.1** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 17+ | 12+ |
| Developer | [Wai Yin Chan](https://appshunter.io/developer/1376527988) | [GCDM Limited](https://appshunter.io/developer/1766019898) |

## What reviewers say

### Shadow Echo

[App page](https://appshunter.io/ios/app/shadow-echo-ai-mystery/id6761412352)

**Features:** macOS Compatibility

**In-app purchases:** none


### 海龜湯 · AI 深夜推理

[App page](https://appshunter.io/ios/app/ai/id6794541468)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 試味 · 9 代幣 | $2.99 | one-time |
| 常客 · 33 代幣 | $9.99 | one-time |
| 老饕 · 81 代幣 | $19.99 | one-time |


## Frequently asked questions

### Is Shadow Echo free?

Shadow Echo is free to download, with no in-app purchases.

### Is 海龜湯 · AI 深夜推理 free?

海龜湯 · AI 深夜推理 is free to download, with in-app purchases available.

### Do Shadow Echo or 海龜湯 · AI 深夜推理 have ads?

Shadow Echo shows ads; 海龜湯 · AI 深夜推理 does not.

### Which is updated more often, Shadow Echo or 海龜湯 · AI 深夜推理?

Shadow Echo ships an update every 3 days, and 海龜湯 · AI 深夜推理 fortnightly. Most recently, Shadow Echo was updated on October 31, 2026 and 海龜湯 · AI 深夜推理 on November 6, 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.*