# D vs NIO Zen Smart Lock

The clearest difference is review sentiment: D at 38% against NIO Zen Smart Lock's 29%. D also leads on iOS requirement (10.0 vs 13.0). On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

D ships an update every 5 weeks, NIO Zen Smart Lock every 2 months. The most recent releases landed on October 7, 2026 and October 12, 2026 respectively.

## The numbers

| Metric | D | NIO Zen Smart Lock |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | **37.5% of reviews** | 28.6% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 5 weeks** | Every 2 months |
| Monetization | Free | Free |
| Size | 23 MB | 13 MB |
| Requires iOS | **10.0** | 13.0 |
| Devices | iPhone, iPod | **iPhone, iPod, Apple Watch** |
| Age rating | 4+ | 4+ |
| Developer | [SECUREMME SRL](https://appshunter.io/developer/1076281466) | [Evva Italia srl](https://appshunter.io/developer/1561615007) |

## What reviewers say

### D

[App page](https://appshunter.io/ios/app/d-smart/id1076281467)

Transform your existing European cylinder locks into smart locks with this device. Control your doors remotely via smartphone, manage access permissions, and create virtual keys. Enjoy convenient and secure access control without needing to replace your current lock.

**Highlights:** Automate European cylinder locks, Smartphone control via Bluetooth, Virtual key creation, Timed access management, User access control, Multiple access methods (transponder, keypad)

**Features:** macOS Compatibility

**In-app purchases:** none


### NIO Zen Smart Lock

[App page](https://appshunter.io/ios/app/nio-zen-smart-lock/id1561615005)

This smart lock system offers automatic locking with high-security modular cylinders. It installs on any door without modifications and can be configured via smartphone or dedicated remote. Access is granted through various methods including biometric and RFID.

**Highlights:** Automatic locking, High-security modular cylinders, Easy installation on any door, Smartphone configuration via Bluetooth, Multiple access methods (RFID, biometric, keypad), Access logging and user management, Long-lasting rechargeable batteries

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is D free?

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

### Is NIO Zen Smart Lock free?

NIO Zen Smart Lock is free to download, with no in-app purchases.

### Do D or NIO Zen Smart Lock have ads?

Neither D nor NIO Zen Smart Lock shows ads.

### Which is updated more often, D or NIO Zen Smart Lock?

D ships an update every 5 weeks, and NIO Zen Smart Lock every 2 months. Most recently, D was updated on October 7, 2026 and NIO Zen Smart Lock on October 12, 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.*