# Knock, knock, knock! vs Polylino

The clearest difference is price: Polylino at Free against Knock, knock, knock!'s $2.99. Polylino also leads on review sentiment (33% vs 0%) and update cadence (every 3 weeks vs every 48 months). Knock, knock, knock!'s advantage is iOS requirement (9.3 vs 15.6). On ads, in-app purchases and device support there is nothing between them.

Polylino is free to download; Knock, knock, knock! costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Knock, knock, knock! ships an update every 48 months, Polylino every 3 weeks. The most recent releases landed on October 8, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | Knock, knock, knock! | Polylino |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | — | **[4.2 (5 ratings)](https://appshunter.io/ios/app/polylino/id1448749849/reviews)** |
| Number of ratings | — | **5** |
| Positive reviews | 0.0% of reviews | **33.3% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 48 months | **Every 3 weeks** |
| Monetization | Paid | **Free** |
| Size | 121 MB | 52 MB |
| Requires iOS | **9.3** | 15.6 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Alfabeta](https://appshunter.io/developer/586381859) | [ILT Inläsningstjänst AB](https://appshunter.io/developer/1277042293) |

## What reviewers say

### Knock, knock, knock!

[App page](https://appshunter.io/ios/app/knock-knock-knock/id586381856)

This interactive book app brings a classic children's story to life with engaging page-turning and the ability to record your own narration. It's designed for young children to enjoy a beloved tale in a new digital format.

**Highlights:** Interactive page turning, Recordable narration, Multiple language options, Classic children's story, Designed for toddlers

**In-app purchases:** none


### Polylino

[App page](https://appshunter.io/ios/app/polylino/id1448749849)

A multilingual digital picture book app designed for educators to use in early childhood classrooms. It offers a library of age-appropriate books with read-aloud or listen options in various languages, supporting emergent literacy and curriculum goals.

**Highlights:** Multilingual digital picture book library, Supports emergent literacy, Culturally diverse books, Picture books and non-fiction, Accessible for all students, Curriculum support

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Knock, knock, knock! free?

Knock, knock, knock! costs $2.99, with no in-app purchases.

### Is Polylino free?

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

### Do Knock, knock, knock! or Polylino have ads?

Neither Knock, knock, knock! nor Polylino shows ads.

### Which is updated more often, Knock, knock, knock! or Polylino?

Knock, knock, knock! ships an update every 48 months, and Polylino every 3 weeks. Most recently, Knock, knock, knock! was updated on October 8, 2026 and Polylino on October 7, 2026.

---

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