# CatchPDF vs Kairox

The clearest difference is update cadence: CatchPDF at every 2 days against Kairox's every 4 days. CatchPDF also leads on iOS requirement (15.1 vs 17.0). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. CatchPDF sells 5 in-app purchases, starting at $3.99 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.

CatchPDF ships an update every 2 days, Kairox every 4 days. The most recent releases landed on November 5, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | CatchPDF | 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 2 days** | Every 4 days |
| Monetization | — | Subscription |
| Size | 103 MB | 18 MB |
| Requires iOS | **15.1** | 17.0 |
| Devices | **iPhone, iPod** | iPhone |
| Age rating | 4+ | 12+ |
| Developer | [hasan cemre kaplan](https://appshunter.io/developer/1863267237) | [Sofia Marin](https://appshunter.io/developer/1849827756) |

## What reviewers say

### CatchPDF

[App page](https://appshunter.io/ios/app/catchpdf-ai-editor-converter/id6760625743)

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

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Premium | $3.99 | per month |
| Annual Premium | $29.99 | per year |
| 100 Tokens | $4.99 | one-time |
| 200 Tokens | $7.99 | one-time |
| 300 Tokens | $9.99 | one-time |


### 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 CatchPDF free?

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

### Is Kairox free?

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

### Do CatchPDF or Kairox have ads?

Neither CatchPDF nor Kairox shows ads.

### Which is updated more often, CatchPDF or Kairox?

CatchPDF ships an update every 2 days, and Kairox every 4 days. Most recently, CatchPDF was updated on November 5, 2026 and Kairox 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.*