Nuki Smart Lock in Test: Opens the door by voice or smartphone

Nuki Smart Lock in Test: Opens the door by voice or smartphone

Tl; dr: The Nuki Smart Lock makes conventional lock cylinders fit for smartphone access. In the test it convinces by a very simple assembly and the compatibility to already installed locking cylinders. Apart from trusting in the technology, however, there is also an easy-going lock.

Smart door lock Nuki Smart Lock in test

Nuki is an electronic door lock that makes conventional locking cylinders fit for smartphone access. The Nuki Smart Lock costs 229 euros, the Nuki Bridge for the remote access to the castle from the way costs 99 euros extra. A bundle of both components offers Nuki for 299 euros.

The development and production of the smart door lock was financed through the crowdfunding platform kickstarter. Nuki is designed to be easier and quicker to install and operate than competitors – the manufacturer speaks of only three minutes, which is necessary for the installation. This is a value which proves to be quite durable in the test.

Whether the own door and the built-in door cylinder are compatible with Nuki, the user can test before purchasing with some questions directly at Nuki. In addition to a suitable cylinder shape, the key itself must not be thicker than 4 mm and its handle should not be longer than 40 mm so that it can be accommodated in the closing unit.

From the outside, the Nuki Castle is not visible unless the door contains any glass elements. If glass elements are present, it should be borne in mind that burglars can open the locked door by turning the Nuki Smart Lock after they have destroyed the glass.


The Nuki Smart Lock comes with two mounting plates to secure it to the door lock. Which mounting plate must be used depends on the overlap of the locking cylinder. If this is less than 3 mm, the mounting plate B is glued to the door or to the lock plate. In the case of a larger overlap, on the other hand, mounting plate A is fastened directly to the overhang of the closing cylinder with three small screws. Drilling or screwing into the door leaf is not absolutely necessary.

When the mounting plate is attached, the normal door key is inserted into the lock. The actual control unit of Nuki is then plugged onto the mounting plate and receives the inserted key in a gap. The motor always turns the key inserted and closes the lock. In this unit, there are four AA batteries, which hold the motor and the data connection via Bluetooth to the smartphone or the Nuki Bridge.

No lockout only with cylinder closable on both sides

In order for the door to be opened from the outside when the electronic door lock is not responding or the batteries are empty, it should be ensured that the lock can be operated from the outside even with a key if a key is inserted on the inside, As is always the case with Nuki.

This emergency and dangling function (also BSZ: cylinders that can be closed on both sides) are not available with all locking cylinders. Nuki himself points out that although these are not necessary for the operation of Nuki, but are recommended.

The calibration and configuration of the Nuki Smart Lock is then fully implemented in the smartphone app under iOS or Android. It guides the user step by step through the necessary settings. This includes, among other things, setting the location of the lock as far as the geofencing possibilities of the lock are concerned, which allow an automatic opening of the door when the user comes home and approaches the door. The lock can be controlled not only via the app, but the door can also be opened and locked by turning the knob or pressing the button on the lock.

Following the Bluetooth configuration of the lock, the user can connect the Nuki Bridge to the lock if purchased. This must be plugged into a socket at a maximum distance of five meters from the lock, and the button on the lock and bridge must be pressed for five seconds. If the two devices are connected to each other, the control of the lock can also be performed over the Internet from the road.

In the default settings with “Auto Unlock” activated, Nuki opens the door as you approach the lock to five meters. For this purpose Bluetooth is also used when geofencing is activated in combination with the bridge, in order to be able to determine the distance to the lock more precisely.

The user can also automatically close the door after 20 seconds. Automatic closing of the door when leaving the house is not done in the default settings. This can and must be activated by the user in the expert settings, but Nuki does not provide any guarantee for their use. The user can additionally or alternatively also activate a warning when he is removed from the lock and is still unlocked.

Encrypted communication

The communication between smartphone and Nuki is completely end-to-end-encrypted and does not give rise to criticism. NaCl is used to encrypt the data, using 32-byte keys and 24-byte nonces. Both the direct communication between the smartphone and Nuki as well as between smartphone, bridge and Nuki is encrypted, so it does not make any difference by which way one sends the commands to the lock. The manufacturer declares the procedure transparent on the homepage.

“Alexa, open the door with Nuki”

The Nuki Smart Lock can be integrated into Smart Home systems via IFTTT, for example to combine the opening of the door with the switching on of Philips Hue lamps. Meanwhile, Nuki also supports the language assistant Amazon Alexa, so that control of the castle via an Amazon echo (dot) is possible.

Please note that the service Nuki Web must be activated before the activation of the skill in the Alexa app, for which the bridge is a prerequisite. Nuki Web is an online platform for managing and managing Nuki Castle. Not only can the settings and the protocol be viewed via this platform, but the lock can also be opened or locked independently of a smartphone.

Alexa can unlock, lock and unlock the door. Lock ‘n’ Go can also be activated, which closes the lock 20 seconds after opening. Also a status query about the current closing state of the lock as well as the last five entries of the lock protocol can be queried via Alexa. To lock, open, and activate Lock ‘n’ Go, the announcement of a previously set PIN is required. After a command that requires a PIN, Alexa explicitly asks for this PIN in the second step. The PIN code for unlocking must be between 4 and 10 digits.

In the test there were no problems with the detection of the PIN and the execution of the command via Alexa. In the evaluation of the Nuki skill, however, there are several evaluations, which are precisely this. If the user does not assign a PIN when setting up the skill, the lock can not be opened via Alexa – a security measure to make it impossible for unauthorized persons to open the door by means of an open window.

Locking the door is also possible without a PIN. The lock offers the possibility to open the door manually at any time by turning the knob on the Nuki Lock so that you can not lock yourself as long as the Smart Lock is not mounted on the wrong side of the door.

The following commands are possible via Alexa:

  • “Alexa, open Nuki.”
  • “Alexa, tell Nuki to shut the door.”
  • “Alexa, open the door with Nuki.” (PIN required)
  • “Alexa, tell Nuki to unlock the door.” (PIN required)
  • “Alexa, unlock the door with Nuki.” (PIN required)
  • “Alexa, tell Nuki to make Lock ‘n’ Go.” (PIN required)
  • “Alexa, ask Nuki for the status.”
  • “Alexa, ask Nuki, who has locked the door.”
  • “Alexa, ask Nuki for the lock protocol.”

everyday experiences

In the test, the opening, locking and unlocking of the door via the app work reliably. Without Nuki Bridge, which connects the electric door lock via Bluetooth to the Internet, the action radius is however very limited. After just a few meters and a wall between Smartphone and Nuki Smart Lock, the lock can not be operated without a bridge, since a stable Bluetooth connection can no longer be built up.

Reliable operation from a distance

This problem solves the Nuki Bridge reliably. Actions can also be started easily and reliably from the road or from far away areas. The fact that the lock does not respond to a command sent via the app did not occur in the test at any time. However, the user should be aware of a good connection and proximity between Bridge and Smart Lock so that both components can always establish a Bluetooth connection.

Nuki Smart Lock in the test

Automatic opening is not always reliable

In individual cases not always worked reliably in the test, but the auto-unlock function, with which the door lock is opened as one approaches. The underlying geofencing itself recognized itself when the 100 m radius (standard setting) was entered. However, the door lock did not always open automatically when it was approached and the smartphone was close enough to the lock to establish a Bluetooth connection. The lock basically differs between “unlocking”, releasing the lock and “opening the door”, in which the closer is also opened, so that the door has only to be pressed.

The lock does not open already when you are within the defined radius (default: 100 m), but only when the user approaches the lock up to five meters. This handling is useful in order to prevent unwanted opening, for example, during the pre-drying or driving.

A smooth-running cylinder is a must

Nuki points out that the closing mechanism must be light, so that the electronic door lock can lock the door automatically. In everyday life, however, this is not always the case at home entrance doors, since wooden doors, for example, are warped depending on the weather and humidity, which can also affect the position of the locking bar. Frequently, doors must be easily used when fitting or closing.

This was the case in the test for Nuki to master – without success. If the locking bar does not close without a little extra effort, Nuki fails to lock the door, but immediately points it out and informs the user. If the Smart Lock is to be used anyway, the door must be modified to make it more easy to lock.

No more keys for guests

In the app, other users can be invited to control Nuki to allow them access to the home or home without giving them a key. Access may also be granted on a limited time or only on certain days at specific times. However, if the owner has not assigned a PIN to the administration area in the app, guests can invite other people to delete other users, even the owner or the lock, and thus lock them out.

The app does not distinguish between the admin and the guest without a PIN, but explicitly draws the user’s attention when inviting additional people. The user must push the warning message with a “No” to set up a PIN to continue, and should take appropriate precautions with a PIN so as not to be blocked by other users.

Nuki Smart Lock: Invite people


The Nuki Smart Lock is characterized by several positive aspects. On the one hand, it can be installed very simply and quickly on most standard doors. On the other hand, you do not need a special locking cylinder, which pushes the price of the electronic door lock even higher, but can use the existing locking cylinder. In order not to run the risk of self-locking, however, the buyer should pay attention to a cylinder with an emergency and hazard function, which can also be closed from the outside when the Nuki is installed.

The Auto-Unlock function, one of the greatest advantages of the smart door lock, worked reliably, but not invariably, in almost all cases. Whether this can be attributed to the structural conditions and work better or worse in other environments can not be said with certainty. However, users do not complain so far that this function is causing problems.

In the event of an emergency, the Smart Lock can be reset

If the user has not set up guest accesses or Nuki Web and deactivated the coupling of new devices at the push of a button, the lock and the user management can no longer be used if the smartphone is lost. In this case, a reset must be made directly at the Nuki Smart Lock. Nuki Web, which makes it possible to manage the castle via a computer, must be explicitly set up by the user and requires the bridge. Data or control options on a Nuki server need not be compulsory.

An easy-going castle is a must

Sluggish locks, which can only be locked by more effort or where the door has to be pressed, can not be locked by Nuki. The electronic lock pushes tirelessly to carry out the closing process, but ultimately fails in the test case at the resistance and informs the user about the unsuccessful attempt. Therefore, prospective buyers should check before the purchase whether the lock can be locked in the ideal case only by turning the key without exerting much force or pressing against the door.

Key substitute for children

If you do not want to give younger children a key, in order not to have to exchange the locking cylinder in case of loss, parents can either put on the smartphone, if the child already has it, or the 40 € small Bluetooth switch Fob , Over which the lock can also be opened.

Besides money, it also needs trust

For the comfort of an automatic opening and closing lock, the user has to pay about 300 euros at Nuki. A priceless price, which only justifies itself when the functions in everyday life are actually used by all persons – and one is so familiar with the technology that one wants to control access to the home through them.

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I'm an avid gamer and a bit of a Ninja when it comes to gadgets and technology. When I'm not busy with the latest Android and iOS games.

1 Comment

  1. Hello I just got one. I am underwhelmed.

    a) Who needs Alexa to open the door from indoors? My door is Multipoint lock, and when closed, I just open with the handle. Using Alexa is ridiculous.

    b) From the outside until now I have only once succeeded to get the door unlocked and opened automatically. All other times I needed to look for the phone, open the app, press the button, wait. Taking a key is 5 times faster. Difficult to explain spending so much money for these two uses.

    c) IF I can get automatic opening from outside to work, I may keep it.

    d) It it works only intermittent, it’s equal to zero. I can’t trust it, and if you cannot trust your lock, use a key.

    So much from a frustrated user….and I am not the only one, and still wanted it.

    And no, I am not new to electronics, engineer, with electronics to drive my wife crazy everywhere. So….the negative feedbacks seem to be well founded……sadly.

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