# Z21

> Wireless model train control and management for Z21 Digital Centers. (iPhone/iPad app by Modelleisenbahn GmbH.)

- Source: https://appshunter.io/ios/app/z21/id1114706450 (this page in markdown: same URL + `.md`)
- Developer: [Modelleisenbahn GmbH](https://appshunter.io/developer/533805542)
- Category: Lifestyle, Entertainment
- Price: Free with in-app purchases
- Rating: 3.77/5 from 13 App Store ratings · 93 written reviews indexed
- Age rating: 4+
- Requires: iOS 12.0 · 232 MB
- Languages: Czech, Dutch, English, French, German, Hungarian, Italian, Polish, Slovak, Spanish
- Released: 2018-01-31
- Data updated: 2026-07-16
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/z21/id1114706450/reviews.md

## What is Z21?

Use this app to connect to a Z21 Digital Center. A demo mode is available.
With this app you can manage locomotive libraries, locomotives and locomotive functions, program digital components – and of course control all locomotives with DCC- or Motorola-decoder, as easy and convenient as is only possible with touch-technology.
The digital switchboard Z21 connects your model train unit and your digital locomotives with your iOS device via WLAN. This way you can control the operation on your train layout easily and conveniently from your mobile device. 

Model train control was never this easy and convenient: With one swipe of your hand you can scroll to your model of choice in the locomotive library. A slight touch on the headlight symbol and the front and backlights go on. A second touch, this time on the speaker symbol, and the locomotive makes a sound. Drag your finger over the speed indicator and the train accelerates. 

The further highlights of the Z21-App
 • Control your entire layout with an intuitive, graphic interface and have easy access to the entire scope of functions of your digital locomotives.
 • Manage your entire locomotive-library in just one application, including individual locomotive images for an ideal overview.
 • Control the digital functions of your locomotives with intuitive function symbols instead of complicated key combinations.
 • Create a blueprint of your railway system and control your switches, signals and modules with a single click.
 • Download driver cabs and control your locomotives from a real train driver’s point of view.

## Key features

- 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

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

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


## What do users think of Z21?

Overall sentiment: mixed

**Pros**

- 👍 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
- 🔧 Easy programming of decoders and functions
- 🎯 Excellent route and turnout management
- 📊 Comprehensive locomotive database with photos
- 🌐 Multi-user support for collaborative operation
- ⚡ Responsive control for sound and lighting functions

**Cons**

- 🐛 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
- 🔋 High battery consumption and device overheating
- 🎨 Limited customization options for layout backgrounds
- 🔄 Data synchronization issues across multiple pages
- ❌ Missing support for competitor decoders (Märklin, Fleischmann)
- 📚 Poor documentation and release notes

**Commonly 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
- Weichen (turnout) display showing white/blank images
- App freezes during speed adjustment
- Export functionality crashes (PRO version)
- Occupancy feedback not displaying (Roco 10808)
- iOS 14+ compatibility issues
- Slow response times and lag
- Layout elements jumping off-screen when editing
- Routes highlighting incorrectly or not at all
- Password-protected bug report zip file inaccessible to users
- Fleischmann turntable module not available
- Bridge modules cannot be displayed diagonally
- Data loss after app updates

**Most 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)
- Pendulum train control functionality
- Manual route deactivation capability
- Larger emergency stop button
- Locomotive database sharing between layouts
- Multi-language support (Spanish, French, Italian, Russian, Japanese)
- Diagonal bridge module display
- Camera locomotive integration
- Double slip switch operation
- Text labeling in layout designer
- Improved signal image selection interface
- Vehicle filtering and categorization system
- Windows/Mac desktop application
- Start-destination buttons for easier route control
- Occupancy feedback module support (Roco 10808)
- Copy and paste functionality in layout mode

## Recent user reviews (10 of 93)

All indexed reviews: https://appshunter.io/ios/app/z21/id1114706450/reviews.md

### 5/5 — Great App

*2026-04-08, version 1.5.3*

Great App. Im happy user. 🙂

### 2/5 — Lost my control station pages after update

*2026-03-03, version 1.5.3*

I had just created a staging yard on a second page in control station and after this update it’s just gone. I spent days and of course I saved it along the way. What happened?

### 5/5 — Good

*2025-06-26, version 1.5.1*

Je to velice jednoduchá aplikace, stejně jako jiné nové věci, člověk si musí zvyknout, ale jakmile si osvojíte veškeré funkce, je to hodně jednoduché a důmyslné ovládání. Třeba nastavení cesty vlaku, pod jednou ikonou, po nastavení, ovládáte neomezené množství prvků. Za mě fakt dobré!!! Jakýkoliv dekodér který jsem doposud přidal ke kolejišti, tak okamžitě funguje jak má. Vyplatí se zaplatit licenci.

### 2/5 — Z21 Fremdzentrale

*2025-06-15, version 1.5.1*

Erkennt meine Z21 als fremdzentrale sobald die App einmal zu war. Muss immer zuerst die App aufmachen und dann die Z21 anschalten. Ultra nervig. Sonst okay.

### 5/5 — Great App

*2025-05-14, version 1.5.1*

Great App.

### 3/5 — Guter Anfang, aber noch viel Luft nach oben

*2025-04-29, version 1.5.1*

Leider warte ich schon beinahe ein halbes Jahr auf meine schwarze Z21. Die Zeit habe ich genutzt, um mich in die App einzuarbeiten, die Gleisschemata zu erstellen und dergleichen. Auffällig: verwendet man für dieselbe Anlage mehrere Seiten im Stellwerk, synchronisiert sich die Anzeige für aktive Fahrstraßen nicht (gleiche Weichenadressen natürlich). Ebenfalls undeutlich, ob durch eine gestellte Weichenstraße andere Züge nicht in diese einfahren bzw. wie man auf durch Belegtmelder/ABC-Steuerung darauf automatisiert reagieren könnte, ohne zusätzlich einen Haufen Technik um die Z21 herumzubauen. Die Doku ist leider auch eher bescheiden, hier erwarte ich in dieser Preisklasse eigentlich etwas mehr. Wäre schön, wenn da Updates kämen, die derartige Probleme beheben (auch auf Dokuseite!)

### 4/5 — Très bien

*2025-04-08, version 1.4.11*

Aucun souci depuis 2ans.

### 3/5 — Verbesserungsfähig

*2025-02-17, version 1.4.10*

Prinzipiell gut, dass man via App die Modellbahn steuern kann. Ideal auch, wenn mal Freunde zu Besuch sind , und man so zu Mehreren realistisch fahren kann.

Aber bei der Usability gibt es Verbesserungsbedarf:

1) Bei der Lok-Steuerung kann man über einen vertikalen Balken durch Hoch- und Runterwischen die Geschwindigkeit verändern. Leider reagiert der Bereich auch auf horizontales Wischen (und im selben Moment dann nicht mehr auf vertikales Wischen) wodurch gerade in Stresssituationen die Geschwindigkeit des Zuges nicht rechtzeitig vermindert werden kann - möglicherweise teure Unfälle sind die Folge. Besser wäre, diesen Bereich für horizontale Bewegungen zu sperren und evtl. den Nothalt (Verminderung der Geschwindigkeit auf 0) automatisch auszulösen, wenn besonders hektisch/ schnell nach unten gewischt wird. 

2.) Auf der selben Seite eine Neupositionierung wichtiger Elemente: Der Stop-Button ist zu klein. Ich erwarte ihn direkt unterhalb des Geschwindigkeitsregelbalkens, so dass man da im Notfall reinwischen kann und die Züge stoppen.
Die Fahrtrichtungswechselpfeile könnte man oben links und rechts neben dem Geschwindikeitsbalken (der nicht nach oben breiter werden müsste) anbringen und das Lokbild oben in die Mitte zwischen „Control“ und „km/h“.
Die Lokbilder unten links und rechts zuschneiden (quadratischer machen), damit mehr auf den schmalen iPhone Display passen)

3) Die Lokdatenbank (bei Lok hinzufügen) offline verfügbar machen. Wenn ich zum Fahrzeughinzufügen im Z21 WLAN bin, würde ich gerne darauf zugreifen können. Filteroptionen und Kategorien wären großartig. Und natürlich sollte eigentlich jedes Modell das Digital verkauft wird, dort zu finden sein.

### 1/5 — Abstürze an der Tagesordnung

*2024-12-01, version 1.4.10*

Auch nachdem ich nun die € 20 bezahlt habe, schuldet ihr mir immer noch eine stabile App, die nicht andauernd abstürzt.

### 1/5 — Dno totalne

*2024-11-29, version 1.4.10*

Zrywa połączenie, nie znajduje lokomotyw a jak znajdzie, nie ma możliwości sterowania🤬 badziew jakich mało!

## Frequently asked questions about Z21

### What does the Z21 app do?

The Z21 app allows you to wirelessly control your model train layout and locomotives using your iOS device. It connects to a Z21 Digital Center via WLAN, enabling you to manage your locomotive library, program digital components, and operate switches and signals with an intuitive touch interface.

### What are the key features of the Z21 app?

Key features include wireless control of locomotives and the entire layout, management of a locomotive library with custom images, programming of digital components, an intuitive graphic interface for controlling switches and signals, and the ability to download driver cabs for a realistic train driver's point of view.

### Is the Z21 app free to use?

The app itself is free to download and use, and includes a demo mode for exploration. However, it is designed to work with a Z21 Digital Center, which is a hardware purchase. There may also be in-app purchases available for additional features or content.

### What devices is the Z21 app compatible with?

The Z21 app is designed for iOS devices and connects to your model train setup via WLAN through a Z21 Digital Center. Specific iOS version compatibility would typically be detailed in the app store listing.

### How does the Z21 app make controlling model trains easier?

The app simplifies model train control through its intuitive touch interface. You can easily scroll through your locomotive library, activate functions like lights and sounds with a single touch, and adjust speed by dragging your finger. Creating a blueprint of your railway system allows for single-click control of switches, signals, and modules.

## Version history (last 5 releases)

### 1.5.4 — 2026-07-16

- New languages: Hungarian, Polish, Slovak
- Bug fixes and stability improvements

### 1.5.3 — 2026-02-23

- Bug fixing fixed IP per layout

### 1.5.2 — 2026-02-16

- Fixed IP address per layout: Easier switching thanks to a configurable IP for each layout with its own Z21.
- New language: Italian — the app is now fully available in Italian.
- Support for Z21 START newGen
- Platform updates: Adjustments for the latest operating system versions to improve support and stability.
- Improvements & bug fixes: Various optimizations and bug fixes for a smoother overall experience.

### 1.5.1 — 2025-04-15

- Various bug fixes and stability improvements

### 1.5.0 — 2025-04-10

It is now possible to add and control the Fleischmann turntable control unit (6915) in the app
    - IMPORTANT: The turntable control unit must be connected via LocoNet

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## More apps by Modelleisenbahn GmbH

- [Z21 mobile](https://appshunter.io/ios/app/z21-mobile/id533805539)
- [Z21 mobile HD](https://appshunter.io/ios/app/z21-mobile-hd/id535465008)
- [Roco NEXT Generation](https://appshunter.io/ios/app/roco-next-generation/id913873900)
- [Z21Updater](https://appshunter.io/ios/app/z21updater/id1463533460)
- [RocoAR](https://appshunter.io/ios/app/rocoar/id1529108412)

All apps by Modelleisenbahn GmbH: https://appshunter.io/developer/533805542

## Related topics

[z21](https://appshunter.io/ios/topics/z21) · [z21 mobile](https://appshunter.io/ios/topics/z21-mobile)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-16.*