# 4thirTEEN vs RecallOS

The clearest difference is in-app purchases: 4thirTEEN at none against RecallOS's 10. 4thirTEEN also leads on ads (none vs shown) and device support (4 vs 2). RecallOS's advantage is update cadence (every 6 days vs every 6 months). On price and iOS requirement there is nothing between them.

Both are free to download. RecallOS sells 10 in-app purchases, starting at $0.99 per month. 4thirTEEN asks for nothing beyond the download.

4thirTEEN ships an update every 6 months, RecallOS every 6 days. The most recent releases landed on November 8, 2026 and November 10, 2026 respectively.

## The numbers

| Metric | 4thirTEEN | RecallOS |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (4 ratings)](https://appshunter.io/ios/app/recallos-nurse-nclex-study/id6771189005/reviews)** |
| Number of ratings | — | **4** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 6 months | **Every 6 days** |
| Monetization | — | Free with in-app purchases |
| Size | 55 MB | 30 MB |
| Requires iOS | 15.1 | **15.0** |
| Devices | **iPhone, iPad, iPod, Apple TV** | iPhone, iPod |
| Age rating | 4+ | 17+ |
| Developer | [4thirTEEN](https://appshunter.io/developer/1830618822) | [Caleb Tolbert](https://appshunter.io/developer/1896773958) |

## What reviewers say

### 4thirTEEN

[App page](https://appshunter.io/ios/app/4thirteen/id6749470655)

**Features:** Vision Pro support

**In-app purchases:** none


### RecallOS

[App page](https://appshunter.io/ios/app/recallos-nurse-nclex-study/id6771189005)

Enhance knowledge retention for students and healthcare professionals with AI-powered study tools. Utilize active recall, adaptive quizzing, and personalized learning paths to master complex subjects and track your progress effectively.

**Highlights:** Daily recall paths, AI-powered study materials, Adaptive quizzing, Smart flashcards, Study Buddy AI, Weakness detection, Progress tracking

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

**In-app purchases (10)**

| Purchase | Price | Billing |
| --- | --- | --- |
| RecallOS+ | $0.99 | per month |
| Recall+ | $1.99 | per month |
| RecallOS Plus | $5.99 | per month |
| RecallOS Pro | $9.99 | per month |
| RecallOS Pro Annual | $99.99 | per year |
| 25 Gem Pack | $0.99 | one-time |
| Streak Restore | $0.99 | one-time |
| 60 Gem Pack | $1.99 | one-time |
| 175 Gem Pack | $4.99 | one-time |
| 400 Gem Pack | $9.99 | one-time |


## Frequently asked questions

### Is 4thirTEEN free?

4thirTEEN is free to download, with no in-app purchases.

### Is RecallOS free?

RecallOS is free to download, with in-app purchases available.

### Do 4thirTEEN or RecallOS have ads?

RecallOS shows ads; 4thirTEEN does not.

### Which is updated more often, 4thirTEEN or RecallOS?

4thirTEEN ships an update every 6 months, and RecallOS every 6 days. Most recently, 4thirTEEN was updated on November 8, 2026 and RecallOS on November 10, 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.*