# Book+ App vs Underline

The clearest difference is in-app purchases: Book+ App at none against Underline's 3. Book+ App also leads on ads (none vs shown) and update cadence (every 3 days vs every 10 days). Underline's advantage is device support (3 vs 1) and iOS requirement (15.5 vs 17.6). On price there is nothing between them.

Both are free to download. Underline sells 3 in-app purchases, starting at $4.99 per month. Book+ App asks for nothing beyond the download.

Book+ App ships an update every 3 days, Underline every 10 days. The most recent releases landed on October 31, 2026 and November 6, 2026 respectively.

## The numbers

| Metric | Book+ App | Underline |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | **Every 3 days** | Every 10 days |
| Size | 18 MB | 49 MB |
| Requires iOS | 17.6 | **15.5** |
| Devices | iPhone | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [premio puzzlemio](https://appshunter.io/developer/1646978163) | [Zeynal Abidin UNLU](https://appshunter.io/developer/6811378018) |

## What reviewers say

### Book+ App

[App page](https://appshunter.io/ios/app/book-plus-app/id6802380574)

**In-app purchases:** none


### Underline

[App page](https://appshunter.io/ios/app/underline-book-quotes-and-notes/id6821564891)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Underline Pro Monthly | $4.99 | per month |
| Underline Pro Yearly | $19.99 | per year |
| Underline Pro Lifetime | $39.99 | one-time |


## Frequently asked questions

### Is Book+ App free?

Book+ App is free to download, with no in-app purchases.

### Is Underline free?

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

### Do Book+ App or Underline have ads?

Underline shows ads; Book+ App does not.

### Which is updated more often, Book+ App or Underline?

Book+ App ships an update every 3 days, and Underline every 10 days. Most recently, Book+ App was updated on October 31, 2026 and Underline on November 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.*