# Isy.AI vs Cairn

The clearest difference is in-app purchases: Isy.AI at none against Cairn's 1. Isy.AI also leads on iOS requirement (16.4 vs 18.0). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. Cairn sells 1 one-off in-app purchase. Isy.AI asks for nothing beyond the download.

Both ship on a similar rhythm, roughly every 3 days. Both last shipped on October 31, 2026.

## The numbers

| Metric | Isy.AI | Cairn |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/isyai-ai-notes-second-brain/id6809262091/reviews)** | — |
| Number of ratings | **2** | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 3 days | Every 3 days |
| Monetization | Free | — |
| Size | 60 MB | 18 MB |
| Requires iOS | **16.4** | 18.0 |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 17+ | 4+ |
| Developer | [Akhil Arunkumar](https://appshunter.io/developer/1877687216) | [Shrey Pinnada](https://appshunter.io/developer/6811047463) |

## What reviewers say

### Isy.AI

[App page](https://appshunter.io/ios/app/isyai-ai-notes-second-brain/id6809262091)

Capture thoughts, voice memos, images, and PDFs, and let AI automatically link them to related past ideas. Engage in conversations with your notes, receive daily digests of connected thoughts, and visualize your knowledge network.

**Highlights:** Automatic note linking and connection, Text, voice, image, and PDF capture, AI-powered chat with your notes, Daily digests of connected ideas, Visual knowledge map, Export notes as Markdown or PDF

**In-app purchases:** none


### Cairn

[App page](https://appshunter.io/ios/app/cairn-your-second-brain/id6811047461)

**Features:** Family Sharing

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Cairn+ Lifetime | $14.99 | one-time |


## Frequently asked questions

### Is Isy.AI free?

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

### Is Cairn free?

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

### Do Isy.AI or Cairn have ads?

Neither Isy.AI nor Cairn shows ads.

### Which is updated more often, Isy.AI or Cairn?

Isy.AI ships an update every 3 days, and Cairn every 3 days. Most recently, Isy.AI was updated on October 31, 2026 and Cairn on October 31, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*