# Hollow Zero vs Kairox

The clearest difference is iOS requirement: Hollow Zero at 14.0 against Kairox's 17.0. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Hollow Zero sells 2 in-app purchases, starting at $12.99 per month and Kairox sells 2 in-app purchases, starting at $5.99 per month. Whichever you choose, the download price is not the number that matters.

## The numbers

| Metric | Hollow Zero | Kairox |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (4 ratings)](https://appshunter.io/ios/app/kairox-quit-doomscrolling/id6766369912/reviews)** |
| Number of ratings | — | **4** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | — | Every 4 days |
| Monetization | — | Subscription |
| Size | 22 MB | 18 MB |
| Requires iOS | **14.0** | 17.0 |
| Devices | **iPhone, iPod** | iPhone |
| Age rating | 4+ | 12+ |
| Developer | [Geronti Liparteliani](https://appshunter.io/developer/1886274741) | [Sofia Marin](https://appshunter.io/developer/1849827756) |

## What reviewers say

### Hollow Zero

[App page](https://appshunter.io/ios/app/hollow-zero/id6761696293)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Hollow Premium Monthly | $12.99 | per month |
| Hollow Premium Yearly | $99.99 | per year |


### Kairox

[App page](https://appshunter.io/ios/app/kairox-quit-doomscrolling/id6766369912)

This app helps you build healthy hydration habits through smart tracking, reminders, and gamified wellness. Log water and electrolytes, build streaks, and unlock achievements with a virtual whale companion. Access requires a subscription or lifetime membership.

**Highlights:** Hydration tracking, Electrolyte logging, Streak building & achievements, Smart reminders, Whale companion gamification, History & insights, Apple Health integration

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Pro | $5.99 | per month |
| Lifetime Pro | $14.99 | one-time |


## Frequently asked questions

### Is Hollow Zero free?

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

### Is Kairox free?

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

### Do Hollow Zero or Kairox have ads?

Neither Hollow Zero nor Kairox shows ads.

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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.*