# Cairn vs Du

The clearest difference is in-app purchases: Du at none against Cairn's 3. Du also leads on ads (none vs shown). Cairn's advantage is update cadence (every 5 days vs every 3 weeks). On price, device support and iOS requirement there is nothing between them.

Both are free to download. Cairn sells 3 in-app purchases, starting at $1.99 per month. Du asks for nothing beyond the download.

Cairn ships an update every 5 days, Du every 3 weeks. The most recent releases landed on October 12, 2026 and October 16, 2026 respectively.

## The numbers

| Metric | Cairn | Du |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | **Every 5 days** | Every 3 weeks |
| Size | 41 MB | 28 MB |
| Requires iOS | **15.0** | 15.1 |
| Devices | **iPhone, iPod, Apple Watch** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Heajung Yoo](https://appshunter.io/developer/1895444232) | [Sindu Menon](https://appshunter.io/developer/1853308943) |

## What reviewers say

### Cairn

[App page](https://appshunter.io/ios/app/cairn/id6767776784)

**Features:** macOS Compatibility, Family Sharing, Apple Watch app, Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Cairn Pro Monthly | $1.99 | per month |
| Cairn Pro yearly | $12.99 | per year |
| Cairn Pro - Ad-free forever | $0.99 | one-time |


### Du

[App page](https://appshunter.io/ios/app/du-it-reminders/id6785280838)

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

**In-app purchases:** none


## Frequently asked questions

### Is Cairn free?

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

### Is Du free?

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

### Do Cairn or Du have ads?

Cairn shows ads; Du does not.

### Which is updated more often, Cairn or Du?

Cairn ships an update every 5 days, and Du every 3 weeks. Most recently, Cairn was updated on October 12, 2026 and Du on October 16, 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.*