# Custom Observer App vs NotiSync

The clearest difference is iOS requirement: Custom Observer App at 15.6 against NotiSync's 18.6. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Custom Observer App ships an update every 3 weeks, NotiSync fortnightly. The most recent releases landed on October 12, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | Custom Observer App | NotiSync |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 weeks | **Fortnightly** |
| Size | 151 MB | 20 MB |
| Requires iOS | **15.6** | 18.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 17+ | 12+ |
| Developer | [Aleut Community of St. Paul Island Tribal Government](https://appshunter.io/developer/1329178887) | [Dingwen Wang](https://appshunter.io/developer/6784461697) |

## What reviewers say

### Custom Observer App

[App page](https://appshunter.io/ios/app/custom-observer-app/id6736385664)

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

**In-app purchases:** none


### NotiSync

[App page](https://appshunter.io/ios/app/notisync/id6784461695)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Custom Observer App free?

Custom Observer App is free to download, with no in-app purchases.

### Is NotiSync free?

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

### Do Custom Observer App or NotiSync have ads?

Neither Custom Observer App nor NotiSync shows ads.

### Which is updated more often, Custom Observer App or NotiSync?

Custom Observer App ships an update every 3 weeks, and NotiSync fortnightly. Most recently, Custom Observer App was updated on October 12, 2026 and NotiSync on October 6, 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.*