# Reef AI vs MistakeBook

The clearest difference is price: Reef AI at Free against MistakeBook's $1.99. Reef AI also leads on update cadence (every 2 weeks vs monthly). MistakeBook's advantage is iOS requirement (13.0 vs 15.1). On ads, in-app purchases and device support there is nothing between them.

Reef AI is free to download; MistakeBook costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Reef AI ships an update every 2 weeks, MistakeBook monthly. Both last shipped on October 31, 2026.

## The numbers

| Metric | Reef AI | MistakeBook |
| --- | --- | --- |
| Price | **Free** | $1.99 |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 weeks** | Monthly |
| Monetization | — | Paid |
| Size | 68 MB | 26 MB |
| Requires iOS | 15.1 | **13.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 17+ | +4 |
| Developer | [Alexandru Ghinea](https://appshunter.io/developer/1880428110) | [Xiamen City Fanyou Network Technology Co., Ltd.](https://appshunter.io/developer/1842524161) |

## What reviewers say

### Reef AI

[App page](https://appshunter.io/ios/app/reef-ai/id6765625125)

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

**In-app purchases:** none


### MistakeBook

[App page](https://appshunter.io/ios/app/mistakebook-wrong-answer-log/id6770173206)

Log and review incorrect answers to improve learning. Organize mistakes by subject and topic, and utilize spaced repetition to reinforce weak areas. Track progress with visual charts and daily check-ins for effective test preparation.

**Highlights:** Log mistakes with photos and notes, Organize by subject and custom tags, Spaced repetition review mode, Ebbinghaus forgetting curve schedule, Progress charts and stats dashboard, Data import/export backup

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

**In-app purchases:** none


## Frequently asked questions

### Is Reef AI free?

Reef AI is free to download, with no in-app purchases.

### Is MistakeBook free?

MistakeBook costs $1.99, with no in-app purchases.

### Do Reef AI or MistakeBook have ads?

Neither Reef AI nor MistakeBook shows ads.

### Which is updated more often, Reef AI or MistakeBook?

Reef AI ships an update every 2 weeks, and MistakeBook monthly. Most recently, Reef AI was updated on October 31, 2026 and MistakeBook on October 31, 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.*