Privacy policy

Last updated: August 22, 2026

The short version

Mozart Benchmark has no accounts, no cookies and no advertising. The only forms on the site are two temporary nicknames: the one used in games with friends, described in point f) below, and the one used on the public leaderboards, the daily challenge and the games alike, described in point g). Neither creates an account, and both disappear the same day. The site uses cookie-free audience measurement (Vercel Web Analytics) which counts visits in aggregate, with no persistent identifier and no cross-site tracking: it is described in detail below. The site collects no other personal data and passes none on for commercial purposes. Your scores and your settings stay in your browser.

What remains regardless, because no site runs in a vacuum, is described below, without playing it down.

Data controller

The publisher of the site, as described in the legal notice. Their public anonymity does not deprive you of a point of contact: for any question about your data, write to contact@mozartbenchmark.com.

What the site processes, in detail

a) The host’s technical logs. The site is hosted by Vercel (United States). Like any host, Vercel keeps technical connection logs (IP address, timestamp, page requested) needed for the security and operation of its infrastructure. Legal basis: legitimate interest. These transfers to the United States are covered by Vercel’s contractual safeguards (European Commission standard contractual clauses) described in its privacy policy. The publisher of the site does not access these logs in order to identify visitors.

b) Cookie-free audience measurement. The site uses Vercel Web Analytics to know its traffic statistics: pages viewed, number of visitors, country of origin, device and browser type, referring site. This tool sets no cookie and writes nothing in your browser. To tell visitors apart, it computes a short-lived identifier server-side (a hash derived from the incoming request) which expires automatically after 24 hours and makes it impossible either to recognise you from one day to the next or to follow you across other sites. The resulting statistics are aggregated and shared with no third party. Legal basis: legitimate interest, understanding how the site is used in order to improve it. The processing is carried out by Vercel under the conditions described in point a) above.

c) Media loaded directly. Music searches go through the site’s own server: Deezer, iTunes and Lyrics.ovh never see your IP address during a search. For the music to play, however, your browser loads the audio clips and the covers directly from Deezer’s delivery servers, and the instrument samples from GitHub Pages. Those providers then receive, as with any web request, your IP address and the technical signature of your browser. Legal basis: legitimate interest, delivering the very content you came to hear. As those servers may sit outside the European Union, this loading may constitute an international transfer; it is governed by the privacy policies of Deezer and GitHub.

d) Your browser’s local storage. The site writes nine keys to your browser’s localStorage: the ambience volume and its on/off state, your progress in the daily challenge, the archive of the previous day’s challenge, your entry on today’s leaderboard, your line on the survival game leaderboards, that is the nickname you published there, the score recorded and a random token that ties that line to you, so that a better run replaces it instead of adding a second one, your choice to show or hide the code of a game with friends, and the result of your last run on each of the two test pages where future games are being built. The site also writes, to the session storage, cleared when the tab closes: the direction of the last transition animation and, during a game with friends, what identifies you to the lobby. This data never leaves your device, is passed to no one and is strictly necessary for the service you are asking for, which is why it requires no consent (article 5(3) of the ePrivacy Directive). You can erase it at any time by clearing your browser’s site data (usually: browser settings, privacy, site data, then mozartbenchmark.com).

e) Emails received. If you write to the contact address, your message and your email address are used to reply to you, and for nothing else. They are deleted once the exchange no longer has a purpose.

f) Games with friends. The site offers private games, opened with a four-character code. To enter one you choose a nickname: freely, with no account, no email address and no password. A nickname is suggested to you at random, so you never have to type your first name, and doing so is not advised. That nickname, your scores for the game and the room code are sent to our host and kept for the duration of the game, then automatically erased. The party closes on its own after ten minutes without activity, and the data disappears from our host at most thirty minutes after the last action. No game history is kept, no named statistics are produced, and your IP address is never linked to your nickname. Your player identity is held in your browser’s sessionStorage, under the key of the current room only, and disappears when you close the tab. Legal basis: performance of the service you are asking for. This point covers only games with friends: the nickname used on the public leaderboards, the daily challenge and the games alike, is a different processing operation, described in point g).

g) Public leaderboards. The site keeps two kinds of leaderboard, and on one point they differ: the daily challenge board, which resets every day, and the survival game boards, which keep the fifty best runs with no time limit. At the end of a round you may choose to appear on one. This is optional: the challenge and the games are played, finished and shared without it. If you accept, you pick a nickname, offered at random, which is then published: it becomes visible to everyone, on the site home page, on the challenge page and on the page of the game concerned. That nickname, your result and the length of your round are sent to our host. For the daily challenge, they are deleted automatically with the board, at the latest thirty-eight hours after universal midnight of the date concerned: no history, no totals, and nothing ties two days together. For the games, they are kept for as long as your run holds in the fifty best, and deleted as soon as it drops out, which happens on its own since only fifty lines are kept. No date is kept there, no total is computed, and nothing ties two runs together. Your own best score is kept by your browser, on your device, as described in point d): that one is never sent anywhere. Nicknames on the boards are filtered automatically before publication, the filter is replayed on every display, and any nickname can be removed on request at contact@mozartbenchmark.com. Finally, so that a single visitor cannot fill a board, a daily counter is kept per connection: your IP address is hashed with a random salt drawn each day and destroyed the next, so that the resulting digest can no longer be tied to anyone. That digest contains no nickname and is attached to no line of any board. Legal basis: performance of the service you are asking for, and legitimate interest for the counter, which preserves the honesty of the boards.

Why there is no cookie banner

This is not an oversight. A banner exists to collect consent for information stored on or read from your device; there is nothing of the sort here to consent to: no cookie, no tracker set, local storage and session storage both exempt because they are strictly necessary, and audience measurement that writes nothing in your browser, creates no persistent identifier and follows no one from one site to another. Showing a banner in these conditions would degrade your visit for nothing, and would be misleading, suggesting processing that does not exist.

Your rights

The GDPR gives you rights of access, rectification, erasure, restriction, objection and portability. Honestly, in context: the site holds no visitor file on which to exercise them, apart from the ephemeral state of a game in progress, which erases itself no later than thirty minutes after the last action; the audience statistics are aggregated and cannot be traced back to any one visitor. Since your scores and settings are stored in your browser, most of these rights are exercised directly, by clearing local storage as described above. You can also object to the audience measurement by using a content blocker: the site works in full without it. For any emails you may have sent, a simple request to the contact address is enough.

Supervisory authority

The authority for the publisher’s place of establishment is the Dutch Autoriteit Persoonsgegevens (autoriteitpersoonsgegevens.nl). You may also contact the authority of your own country of residence, for French visitors the CNIL (cnil.fr).

Minors

The site collects no declared data apart from the temporary nickname used in games with friends, creates no account, and has no messaging, no profile and no published content. A game is played between people who exchanged its code away from the site. As no processing is based on consent, the question of the digital age of consent does not arise.

Changes to this policy

Should the site ever change in nature, advertising, accounts, a more intrusive measurement tool, this page would be updated before the change, and any tracker subject to consent would only be set once that consent had been obtained. The date at the top of the page is the version in force.