January 11, 2026, 12:05 pm | Read time: 4 minutes
The house key is one of those things you often search for when your hands are full. Smart locks promise relief here and aim to make everyday life more convenient—without compromising security. They open the door via smartphone, code, or automatically when you come home, all without traditional unlocking. But how reliably does this work in everyday life? And which models are truly suitable for use on apartment or house doors?
How a Digital Lock Works
Smart locks are electronic attachments or cylinders that are mounted on existing doors. They turn the existing key in the lock using a motor or completely replace the lock cylinder. The whole system is controlled via an app on the smartphone, sometimes even automatically when you approach the door. Additionally, temporary access can often be set up for family, guests, or service providers. For many users, the appeal mainly lies in being more flexible and worrying less about lost keys.
The 3 Best Models in the Test
A test by Computer BILD (also part of Axel Springer) shows that three models stand out for reliability, comfort, and everyday usability. All come from the same manufacturer but differ in detail.
1. Nuki Smart Lock Pro (5th Generation)
The Nuki Smart Lock Pro of the fifth generation is aimed at users who want to retrofit their existing door without major modifications. The lock is mounted from the inside and is hardly noticeable due to its relatively compact design. In everyday use, it scores with features like automatic opening when coming home and the ability to integrate accessories such as keypads or remote controls. The app operation is clear and understandable even for beginners. Limitations exist with the built-in battery and motor performance, which can reach their limits with stiff doors.
2. Nuki Smart Lock Ultra
The Smart Lock Ultra from Nuki features a particularly sleek knob design, giving it a very high-quality appearance. However, this requires replacing the lock cylinder, which is included in the package. In everyday use, the model offers the same comfort as the Pro model, such as automatic unlocking and integration into modern smart home systems. Additional control elements can also be added, for example, for guests without a smartphone. As with the Pro, the battery is not replaceable, and the motor is somewhat less powerful than in older generations.
3. Nuki Smart Lock Pro (4th Generation)
The fourth generation of the Smart Lock Pro is technically a bit older but remains a solid option. It also supports modern radio standards and does not require mandatory registration or cloud connection. In everyday use, the lock impresses with reliable opening and closing and flexible access options for multiple people. The wide range of accessories that can be easily retrofitted is practical. Drawbacks are mainly in the noise level when locking and the rather modest motor performance.
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How Was It Tested?
The test focused mainly on practical criteria. It examined how easy the locks are to install and set up and how understandable the respective app is. Daily use also played a role: How reliably do the locks open and close, how do they interact with the smartphone, and how comfortable is the operation in everyday life? Additionally, aspects such as expandability and connection stability were included in the evaluation.
Conclusion
Smart locks can significantly ease everyday life, especially for people who often come home with full hands or want to grant access flexibly. It is important to check before purchasing whether the respective model fits your door and whether a cylinder replacement is necessary. The questions of battery, noise level, and motor performance also play a role in daily use. Those who value comfort and modern smart home integration will find convincing solutions in the tested models. Ultimately, the deciding factor is which features are truly used in one’s own daily life.