Klaviero
Last updated: 3 August 2026
This policy explains the cookies and local storage used by the Klaviero application and website (the "Service"), operated by La Lumière Consulting SRL, together with the account data described in our Privacy Policy.
Storage falls into three groups. The first is strictly necessary to provide the functionality you request, such as keeping you signed in and remembering your settings and progress. Under Article 5(3) of the ePrivacy Directive that storage does not by itself require consent. The second is a single item we use to count visits to this site, described in Section 2. The third is audience measurement provided by Google Analytics and Microsoft Clarity, which is not strictly necessary, requires your consent, and is set only if you choose "Accept all" in the privacy notice.
If you choose "Only essential" or "Decline", no Google or Microsoft cookie is set, neither tool is loaded, and no request is made to either company at all. Their scripts, including Google Tag Manager, are added to the page only after you accept, so if you refuse, your IP address is never sent to them for this purpose. The Service works the same either way. The single visit-counting item in Section 2 is separate from that choice, and Section 2 explains what it is and why.
We do not run advertising on the Service and we do not profile you. You should know one thing before accepting: Microsoft Clarity sets cookies on Microsoft's own domains, listed in Section 3, which Microsoft also uses to recognise browsers for advertising on other websites. We do not receive that data and we do not use it. It is set only if you accept, and refusing prevents it.
The following items are stored in your browser (in localStorage, in sessionStorage, and in the browser's offline cache) regardless of your choice, because the Service cannot run without them. They are not transmitted to third parties for advertising or analytics purposes.
| Item | Purpose |
|---|---|
nk-token | Maintains your authenticated session so you remain signed in. |
nk-plan | Records your subscription status so the Service functions when offline. |
nk-history, nk-profile, nk-library | Store your practice history, level and imported pieces. |
nk-theme and related settings | Store your display preferences. |
| Offline app cache | Stores the application files and the pages you have already visited, so the Service opens and works without a connection. It never holds requests to our API. |
| Session-only items (sessionStorage) | Hold short-lived state for the current tab, such as whether a guest run is in progress. Cleared when you close the tab. |
nk-cookie-ack, nk-consent | Record that you have seen the privacy notice and the choice you made (accept all, essential only, or decline), so that you are not asked again and so that your choice can be applied on every later visit. |
You may delete this storage at any time through your browser settings. Doing so will end your session and reset your preferences, including your privacy choice, which you will then be asked to make again.
One further item is stored in your browser whatever choice you make in the privacy notice.
| Item | Purpose | Duration |
|---|---|---|
nk-vid (localStorage) | Holds a random number generated in your browser, with nothing in it derived from you or your device. It lets us count how many separate people visited, rather than how many times the page was opened, and see which of our own pages were used. It is how we know whether the Service is being found at all. | 13 months, after which it is discarded and a new number begins. |
This is exempt from the consent requirement in Article 5(3) of the ePrivacy Directive, on the conditions that European data protection authorities set for first-party audience measurement, and we hold ourselves to all of them:
You can remove it at any time by clearing your browser storage, and you can prevent it from being stored at all by using your browser's private mode, in which case nothing is retained between visits.
The following cookies are set only if you choose "Accept all". They are not set if you choose "Only essential" or "Decline", and in that case neither Google Analytics nor Microsoft Clarity is loaded at all.
| Item | Provider | Purpose | Duration |
|---|---|---|---|
_ga, and a second cookie named _ga_ followed by our Google Analytics measurement ID with its G- prefix removed (for example _ga_ABC1234567) | Google Analytics (Google Ireland Limited / Google LLC) | Distinguish one visitor from another and hold the state of a visit, so that page views can be counted. | 13 months. |
_clck | Microsoft Clarity (Microsoft Ireland Operations Limited / Microsoft Corporation) | Holds a Clarity user identifier for this site, so that repeat visits are attributed to the same pseudonymous user. | 1 year. |
_clsk | Microsoft Clarity | Connects several page views by the same visitor into a single session recording. | 1 day. |
CLID, ANONCHK, MR, MUID, SM | Microsoft Clarity, set on Microsoft domains rather than on klaviero.com | Identify the browser across websites that use Clarity and synchronise that identifier between Microsoft domains. MUID is described by Microsoft as also used for advertising and site analytics on Microsoft's own services. We neither receive nor use that data. Microsoft publishes the current list of these cookies in its Clarity cookie documentation. | Set and expired by Microsoft, which does not publish the periods in that list. Because they are stored on Microsoft domains, we cannot delete them for you; withdrawing your consent instructs Microsoft to clear them. |
Google Tag Manager, which loads the Google Analytics tag, sets no cookies of its own. It is itself loaded only after you accept.
Google's advertising consent signals (ad_storage, ad_user_data and ad_personalization) are set to denied at all times, including when you accept analytics, so the measurement data is not used to personalise advertising.
Microsoft Clarity masks input fields and drop-down menus in every configuration, and we additionally mark every field that can hold personal data, such as email, username, password, nickname and friend search, so that its contents are never transmitted to Microsoft.
Separately from the analytics in Section 3, two further services set their own cookies, and only when you actively use them:
These providers act as recipients for the specific function you initiate. We do not control the cookies they set.
You can change your privacy choice at any time, without clearing your browser storage. Open Account and select "Privacy choices" at the foot of the panel, then pick again. You do not need to be signed in: the choice belongs to the browser, not to the account.
Turning analytics off takes effect immediately. The tools stop running in that session, the cookies set on klaviero.com are deleted, Microsoft is instructed to clear the cookies held on its own domains, and nothing analytics-related is loaded on later visits. Turning analytics on takes effect immediately as well.
If we introduce further non-essential storage or any advertising in the future, we will update this policy and ask for your consent beforehand. Where a change means an earlier choice can no longer be treated as informed, we will ask you to choose again rather than carry the old answer forward.