# Posso Parent App vs OnBook

The clearest difference is in-app purchases: Posso Parent App at none against OnBook's 3. Posso Parent App also leads on iOS requirement (15.6 vs 26.0). OnBook's advantage is update cadence (every 5 days vs every 2 months). On price, ads and device support there is nothing between them.

Both are free to download. OnBook sells 3 one-off in-app purchases. Posso Parent App asks for nothing beyond the download.

Posso Parent App ships an update every 2 months, OnBook every 5 days. The most recent releases landed on October 24, 2026 and October 5, 2026 respectively.

## The numbers

| Metric | Posso Parent App | OnBook |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 5 days** |
| Size | 142 MB | 39 MB |
| Requires iOS | **15.6** | 26.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 12+ | 4+ |
| Developer | [Taidii Pte Ltd](https://appshunter.io/developer/921378893) | [Jinyoung Jang](https://appshunter.io/developer/1888765890) |

## What reviewers say

### Posso Parent App

[App page](https://appshunter.io/ios/app/posso-parent-app/id1038708557)

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

**In-app purchases:** none


### OnBook

[App page](https://appshunter.io/ios/app/onbook/id6761301818)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Ink 30 Pack | $2.99 | one-time |
| Ink 70 Pack | $4.99 | one-time |
| Ink 170 Pack | $9.99 | one-time |


## Frequently asked questions

### Is Posso Parent App free?

Posso Parent App is free to download, with no in-app purchases.

### Is OnBook free?

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

### Do Posso Parent App or OnBook have ads?

Neither Posso Parent App nor OnBook shows ads.

### Which is updated more often, Posso Parent App or OnBook?

Posso Parent App ships an update every 2 months, and OnBook every 5 days. Most recently, Posso Parent App was updated on October 24, 2026 and OnBook on October 5, 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.*