# Z21 vs Stamp Identifier · Stamp Value

The clearest difference is rating: Z21 at 3.8 against Stamp Identifier · Stamp Value's 1.0. Z21 also leads on update cadence (every 3 weeks vs every 8 months) and ratings volume (13 vs 1). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Z21 sells 1 one-off in-app purchase and Stamp Identifier · Stamp Value sells 2 in-app purchases, starting at $4.99 per 7 days. Whichever you choose, the download price is not the number that matters.

Z21 holds the better App Store score, 3.8 against 1.0. That said, the two scores are not equally well evidenced: Z21 has 13 ratings behind it against 1, so its average is the more settled of the two.

Z21 ships an update every 3 weeks, Stamp Identifier · Stamp Value every 8 months. The most recent releases landed on October 19, 2026 and October 12, 2026 respectively.

## The numbers

| Metric | Z21 | Stamp Identifier · Stamp Value |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.8 (13 ratings)](https://appshunter.io/ios/app/z21/id1114706450/reviews)** | [1.0 (1 ratings)](https://appshunter.io/ios/app/stamp-identifier-stamp-value/id6756225350/reviews) |
| Number of ratings | **13** | 1 |
| Positive reviews | 38.3% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 3 weeks** | Every 8 months |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Size | 232 MB | 49 MB |
| Requires iOS | **12.0** | 15.1 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Modelleisenbahn GmbH](https://appshunter.io/developer/533805542) | [Andrii Kulchytskyi](https://appshunter.io/developer/1759867572) |

## What reviewers say

### Z21

[App page](https://appshunter.io/ios/app/z21/id1114706450)

Control your model train layout and locomotives wirelessly from your iOS device. Manage your locomotive library, program digital components, and operate switches and signals with an intuitive touch interface. Enjoy a realistic train control experience with customizable driver cabs.

**Highlights:** Wireless control of locomotives and layout, Manage locomotive library with images, Program digital components, Intuitive graphic interface for switches and signals, Downloadable driver cabs for realistic control, Demo mode available

**Features:** Family Sharing

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Z21 Full Version | $17.99 | one-time |

**What reviewers like**

- 👍 Intuitive and user-friendly interface
- 🚀 Fast and reliable locomotive control
- 💡 Innovative layout design with schematic control station
- 🎨 Clean, modern orange and black design
- 📱 Works seamlessly across multiple iOS devices

**What reviewers complain about**

- 🐛 Frequent app crashes and freezes
- 🔌 Connection drops to Z21 control station
- ⚠️ White screen startup issues in recent updates
- 🎮 Throttle display bugs showing incorrect speeds
- 📉 Slow performance on older devices

**Reported bugs**

- App crashes on startup (white screen issue)
- Connection drops to Z21 central station
- Throttle display shows incorrect or blank speeds
- Function buttons not responding properly in multitraction mode
- Route synchronization failures across multiple control station pages

**Requested features**

- Offline locomotive database access
- Dark mode or customizable color schemes
- Background image support for layout design
- Turntable/rotary module support
- Automatic event-based control (occupancy detection, crossing automation)


### Stamp Identifier · Stamp Value

[App page](https://appshunter.io/ios/app/stamp-identifier-stamp-value/id6756225350)

Instantly identify stamps using AI by scanning them with your device. Get detailed catalog information, rarity indicators, and value guidance. Organize your collection, compare similar stamps, and learn philatelic terms.

**Highlights:** AI-powered stamp recognition, Catalog-style details and value guidance, Rarity indicators and condition notes, Collection organization (folders, wishlists), Side-by-side comparison of similar stamps, Offline functionality for core features, Privacy-first design with on-device processing

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Stamp Identifier Weekly 3 days free | $4.99 | per 7 days |
| Stamp Identifier Yearly | $19.99 | per year |


## Frequently asked questions

### Is Z21 free?

Z21 is free to download, with in-app purchases available.

### Is Stamp Identifier · Stamp Value free?

Stamp Identifier · Stamp Value is free to download, with in-app purchases available.

### Which has better reviews, Z21 or Stamp Identifier · Stamp Value?

Z21 is rated higher. Z21 averages 3.8 out of 5 from 13 ratings, while Stamp Identifier · Stamp Value averages 1.0 from 1 ratings.

### Do Z21 or Stamp Identifier · Stamp Value have ads?

Neither Z21 nor Stamp Identifier · Stamp Value shows ads.

### Which is updated more often, Z21 or Stamp Identifier · Stamp Value?

Z21 ships an update every 3 weeks, and Stamp Identifier · Stamp Value every 8 months. Most recently, Z21 was updated on October 19, 2026 and Stamp Identifier · Stamp Value on October 12, 2026.

---

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