# Echo vs Quantum Number Lock

The clearest difference is in-app purchases: Quantum Number Lock at none against Echo's 1. Quantum Number Lock also leads on ads (none vs shown) and iOS requirement (15 vs 17.0). Echo's advantage is update cadence (every 4 days vs every 9 days). On price and device support there is nothing between them.

Both are free to download. Echo sells 1 one-off in-app purchase. Quantum Number Lock asks for nothing beyond the download.

Echo ships an update every 4 days, Quantum Number Lock every 9 days. The most recent releases landed on September 9, 2026 and September 22, 2026 respectively.

## The numbers

| Metric | Echo | Quantum Number Lock |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | **Every 4 days** | Every 9 days |
| Size | 13 MB | 7 MB |
| Requires iOS | 17.0 | **15** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Thorsten Halle](https://appshunter.io/developer/1881398429) | [特 郑](https://appshunter.io/developer/1881393610) |

## What reviewers say

### Echo

[App page](https://appshunter.io/ios/app/echo-pattern-game/id6760206563)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Echo Pro | $2.99 | one-time |


### Quantum Number Lock

[App page](https://appshunter.io/ios/app/quantum-number-lock/id6760518803)

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

**In-app purchases:** none


## Frequently asked questions

### Is Echo free?

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

### Is Quantum Number Lock free?

Quantum Number Lock is free to download, with no in-app purchases.

### Do Echo or Quantum Number Lock have ads?

Echo shows ads; Quantum Number Lock does not.

### Which is updated more often, Echo or Quantum Number Lock?

Echo ships an update every 4 days, and Quantum Number Lock every 9 days. Most recently, Echo was updated on September 9, 2026 and Quantum Number Lock on September 22, 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.*