# DermaDuell vs klang²

The clearest difference is in-app purchases: DermaDuell at none against klang²'s 10. DermaDuell also leads on iOS requirement (13.0 vs 15.6). klang²'s advantage is update cadence (every 2 months vs every 4 months). On price, ads and device support there is nothing between them.

Both are free to download. klang² sells 10 one-off in-app purchases. DermaDuell asks for nothing beyond the download.

DermaDuell ships an update every 4 months, klang² every 2 months. The most recent releases landed on October 11, 2026 and October 2, 2026 respectively.

## The numbers

| Metric | DermaDuell | klang² |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 2 months** |
| Monetization | Free | — |
| Size | 10 MB | 89 MB |
| Requires iOS | **13.0** | 15.6 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 17+ | 4+ |
| Developer | [DocCheck AG](https://appshunter.io/developer/1785591806) | [Oberlin & Rennertz GmbH](https://appshunter.io/developer/1474108830) |

## What reviewers say

### DermaDuell

[App page](https://appshunter.io/ios/app/dermaduell/id973158384)

Test your dermatology knowledge against colleagues in fast-paced quizzes. Earn points and achievements by answering questions across 12 categories. This app is exclusively for registered users of the Dermingo training platform.

**Highlights:** 12 dermatology, product knowledge, and customer advice categories, Over 1,500 unique questions, 5 question rounds per duel, 20-second time limit per question, 85 unlockable achievements, Earn reward points for in-app shop

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

**In-app purchases:** none


### klang²

[App page](https://appshunter.io/ios/app/klang/id1491987376)

**In-app purchases (10)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Klang2 Pro Option 0 | Free | one-time |
| Klang2 Pro Option 1 | $0.99 | one-time |
| Bundesländer und Hauptstädte | $0.99 | one-time |
| Klang2 Pro Option 2 | $1.99 | one-time |
| Klang2 Pro Option 3 | $3.99 | one-time |
| Volkslieder Premium | $3.99 | one-time |
| Tierisch Menschlich | $3.99 | one-time |
| Klang2 Pro Option 4 | $7.99 | one-time |
| Klang2 Pro Option 5 | $11.99 | one-time |
| Klang2 Pro Option 6 | $16.99 | one-time |


## Frequently asked questions

### Is DermaDuell free?

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

### Is klang² free?

klang² is free to download, with in-app purchases available.

### Do DermaDuell or klang² have ads?

Neither DermaDuell nor klang² shows ads.

### Which is updated more often, DermaDuell or klang²?

DermaDuell ships an update every 4 months, and klang² every 2 months. Most recently, DermaDuell was updated on October 11, 2026 and klang² on October 2, 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.*