# Reef Book vs Reef Stability

The clearest difference is price: Reef Stability at Free against Reef Book's $5.99. Reef Stability also leads on update cadence (weekly vs every 6 months) and iOS requirement (18.0 vs 26.0). Reef Book's advantage is in-app purchases (none vs 3) and device support (3 vs 1). On ads there is nothing between them.

Reef Stability is free to download; Reef Book costs $5.99 up front. Reef Stability sells 3 in-app purchases, starting at $6.99 per month. Reef Book asks for nothing beyond the download.

Reef Book ships an update every 6 months, Reef Stability weekly. The most recent releases landed on October 25, 2026 and October 11, 2026 respectively.

## The numbers

| Metric | Reef Book | Reef Stability |
| --- | --- | --- |
| Price | $5.99 | **Free** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 6 months | **Weekly** |
| Size | 166 MB | 9 MB |
| Requires iOS | 26.0 | **18.0** |
| Devices | **iPhone, iPad, Mac** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [ReefSoft LLC](https://appshunter.io/developer/1789068807) | [YUSUF AYDIN](https://appshunter.io/developer/6771871523) |

## What reviewers say

### Reef Book

[App page](https://appshunter.io/ios/app/reef-book/id6740756140)

**Features:** iMessage stickers

**In-app purchases:** none


### Reef Stability

[App page](https://appshunter.io/ios/app/reef-stability-dosing-tracker/id6799461220)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium Monthly | $6.99 | per month |
| Premium Annual | $39.99 | per year |
| Premium Lifetime | $89.99 | one-time |


## Frequently asked questions

### Is Reef Book free?

Reef Book costs $5.99, with no in-app purchases.

### Is Reef Stability free?

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

### Do Reef Book or Reef Stability have ads?

Neither Reef Book nor Reef Stability shows ads.

### Which is updated more often, Reef Book or Reef Stability?

Reef Book ships an update every 6 months, and Reef Stability weekly. Most recently, Reef Book was updated on October 25, 2026 and Reef Stability on October 11, 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.*