# zZz vs Marrow

The clearest difference is update cadence: zZz at every 4 days against Marrow's every 8 days. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. zZz sells 1 one-off in-app purchase and Marrow sells 2 in-app purchases, starting at $9.99 per 7 days. Whichever you choose, the download price is not the number that matters.

zZz ships an update every 4 days, Marrow every 8 days. The most recent releases landed on October 24, 2026 and October 13, 2026 respectively.

## The numbers

| Metric | zZz | Marrow |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[2.9 (11 ratings)](https://appshunter.io/ios/app/zzz-sleep-tracker-widget/id1586436109/reviews)** | — |
| Number of ratings | **11** | — |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 4 days** | Every 8 days |
| Monetization | Free with in-app purchases | — |
| Size | 6 MB | 1 MB |
| Requires iOS | **16.0** | 17.0 |
| Devices | **iPhone, iPad** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Florian Schweizer](https://appshunter.io/developer/1142213239) | [Linh Phan Nhat Khanh](https://appshunter.io/developer/1777727575) |

## What reviewers say

### zZz

[App page](https://appshunter.io/ios/app/zzz-sleep-tracker-widget/id1586436109)

Easily log your sleep with a single tap using home or lock screen widgets. Track time in bed, awake time, and actual sleep duration, syncing data with Apple Health for insightful analysis.

**Highlights:** One-tap sleep logging, Home and lock screen widgets, Tracks time in bed, awake, and sleep, Syncs with Apple Health, Siri and Shortcuts integration

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro Tier | $0.99 | one-time |


### Marrow

[App page](https://appshunter.io/ios/app/marrow-calcium-tracker/id6773758848)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Marrow Bone Health Weekly | $9.99 | per 7 days |
| Marrow Bone Health Yearly | $49.99 | per year |


## Frequently asked questions

### Is zZz free?

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

### Is Marrow free?

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

### Do zZz or Marrow have ads?

Neither zZz nor Marrow shows ads.

### Which is updated more often, zZz or Marrow?

zZz ships an update every 4 days, and Marrow every 8 days. Most recently, zZz was updated on October 24, 2026 and Marrow on October 13, 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.*