Fair Divider collects the minimum data necessary to provide the fair division service:
Participant names — entered by users when creating a division session. These may be real names or pseudonyms.
Division data — total amount to divide, item/room descriptions, choices made per turn, timestamps, and division state.
Technical data — IP addresses are processed by our server to handle REST API requests at /api/v1 but are not stored in our database beyond short-lived security logs.
Owner token — when you create a session, the server generates a random UUID called the "owner token" and returns it to your browser. The token is stored in sessionStorage under the key fairDivisionApiState and is required to perform privileged operations on the session you created. It is never shared with other participants.
Local storage — we use your browser localStorage (key fairDivision_<roomId>) to enable session reconnection in multi-device mode. This data stays on your device.
Optional analytics data — only if you opt in, the website's analytics tools process aggregate usage data and on-page interactions. This is described in section 7 and never occurs without your consent.
We do not collect email addresses, phone numbers, payment information, location data, or require user accounts.
3. How We Use Your Data
Providing the service — processing division sessions, synchronizing multi-device turns, and calculating fair divisions.
Technical operation — server logging for error detection and security monitoring.
Optional analytics — if and only if you opt in, understanding aggregate usage to improve the website (see section 7).
4. Legal Basis (GDPR Art. 6)
Legitimate interest (Art. 6.1.f) — for providing the core fair division service and maintaining server security.
Consent (Art. 6.1.a) — for the optional website analytics described in section 7 (Google Analytics 4 and Microsoft Clarity). These load only if you opt in, are off by default, and can be switched off again at any time. Under Article 22 of the Spanish LSSI-CE, non-essential cookies require your prior consent.
5. Data Retention
Division sessions are automatically deleted after 7 days from creation.
In-memory sessions (when database is not used) are deleted after 2 hours of inactivity.
Server logs are retained for a maximum of 7 days.
Local storage on your device persists until you clear your browser data or the session expires.
Optional analytics data is retained by the relevant provider: approximately 14 months for Google Analytics and approximately 90 days for Microsoft Clarity (see section 7). No analytics data is collected unless you opt in.
6. Cookies and Similar Technologies
Fair Divider relies on strictly necessary cookies and equivalent storage technologies, which are exempt from prior consent under Article 22.2 of the Spanish LSSI-CE and the AEPD 2023 Cookie Guide. The website additionally offers optional analytics cookies that load only after you opt in, as described in section 7. The full inventory (strictly necessary own cookies, Cloudflare Turnstile cookies served on the multi-device page, browser-storage entries, and the optional analytics cookies set only after opt-in) is documented in our Cookie Policy.
We do not use advertising cookies, tracking pixels, or third-party cookies for profiling or behavioural advertising. The only non-essential technologies are the optional analytics described in section 7, which run solely with your consent. Cloudflare Turnstile is loaded on /multi for anti-abuse purposes only and sets no analytics or advertising cookies.
7. Optional Analytics (With Your Consent)
In addition to the strictly necessary technologies above, the Fair Divider website can load two optional analytics tools. They are disabled by default and run only after you give explicit consent.
Google Analytics 4 — provided by Google Ireland Limited, acting as our data processor. It produces aggregate usage statistics (for example, which pages are visited and from which country). Google Analytics 4 does not store raw IP addresses.
Microsoft Clarity — provided by Microsoft Ireland Operations Limited, acting as our data processor. It produces heatmaps and session replay (a reconstruction of on-page interactions such as clicks and scrolling). Clarity masks the content of input boxes and drop-down menus in every masking mode, and we additionally apply Clarity's element-level masking to the calculator itself — the setup form, the division, the proposal and the result — so participant names, item descriptions and amounts are not uploaded to Clarity. Clarity does record the address of the page you are on, the page you arrived from, your browser and device, and an approximate location derived from your IP address. Note that names and amounts are still sent to our own servers to compute the division, as described in sections 2 and 5; the masking above concerns only what Clarity receives.
Legal basis — your consent (Art. 6.1.a GDPR; Art. 22 LSSI-CE, which requires prior opt-in for non-essential cookies). When you first use the website we ask whether to enable analytics. You can choose "Accept all" (strictly necessary + analytics) or "Essential only" (no analytics); analytics stays off unless you opt in. Your choice is stored in your browser under the fd-analytics key.
Withdrawing consent. You can change your mind at any time — withdrawing is as easy as giving consent. Use the "Cookie settings" link in the footer of the Fair Divider app (the calculator pages) to reopen the chooser and switch analytics off; the analytics tools will no longer load.
International transfers. Google and Microsoft may process analytics data outside the European Economic Area (for example, in the United States) under the EU Standard Contractual Clauses and/or the EU-US Data Privacy Framework, in accordance with Chapter V of the GDPR.
Retention. Google Analytics data is retained for approximately 14 months; Microsoft Clarity data is retained for approximately 90 days (the providers' configured/standard retention periods).
8. Data Sharing
We do not sell, rent, or share your personal data with third parties. Our infrastructure providers process data on our behalf:
Hetzner Online GmbH (Germany, EU) — server hosting
Cloudflare, Inc. (USA, with EU processing and Standard Contractual Clauses) — CDN, DNS, and DDoS protection
MongoDB, Inc. (Atlas EU region) — database hosting
If you opt in to the optional website analytics described in section 7, Google Ireland Limited (Google Analytics 4) and Microsoft Ireland Operations Limited (Microsoft Clarity) also act as data processors on our behalf. We never sell your personal data.
9. International Transfers
Your data is primarily processed within the European Union (Hetzner Germany, MongoDB Atlas EU). Cloudflare may process traffic through global edge servers under Standard Contractual Clauses (SCCs) compliant with GDPR Chapter V.
If you opt in to optional analytics, Google and Microsoft may also process data outside the EEA (for example, in the United States) under the EU Standard Contractual Clauses and/or the EU-US Data Privacy Framework, as detailed in section 7.
10. Your Rights (GDPR Articles 15-22)
You have the right to:
Access — request a copy of your data
Rectification — correct inaccurate data
Erasure — request deletion of your data (sessions auto-delete after 7 days)
Restriction — limit how we process your data
Portability — receive your data in a structured format
Objection — object to processing based on legitimate interest
Withdraw consent — withdraw your analytics consent at any time via the "Cookie settings" link in the footer of the Fair Divider app, without affecting the lawfulness of processing before withdrawal
To exercise any right, contact privacy@fairdivider.com with your division session code. We will respond within 30 days.
How to exercise your rights: Send an email to privacy@fairdivider.com identifying yourself. We will respond within a maximum of 1 month as required by Article 12.3 GDPR. If your request requires extraordinary complexity, we may extend this period by up to 2 additional months with prior notice.
11. Right to Complain
You have the right to lodge a complaint with the Spanish Data Protection Agency (AEPD) at www.aepd.es, or with your local supervisory authority.
12. Children
Fair Divider is not directed at children under 16 years of age. We do not knowingly collect data from children.
13. Automated Decision-Making
Fair Divider uses a mathematical optimization to calculate fair divisions. This is a mathematical computation, not profiling or automated decision-making with legal effects as defined in GDPR Art. 22.
14. Mobile Apps
The Fair Divider apps for iOS and Android use the same /api/v1 backend described in this policy. Unlike the website, the native apps do not include the optional analytics described in section 7: they do not collect any additional personal data, do not use Google Analytics, Microsoft Clarity, or any other third-party analytics or advertising SDK, and do not request device permissions beyond what is strictly required for the user-initiated action (for example, sharing a room link). Diagnostic data sent by the operating system to its respective app store (Apple App Analytics, Google Play Console) is governed by the privacy policies of Apple and Google respectively, and not by Binary Spirit S.L.
15. Account & Data Deletion
Fair Divider does not require a user account. Server-side division sessions auto-expire after 7 days. To delete your data sooner, or to remove all locally stored data on your device, see our dedicated Account & Data Deletion page.
16. Changes to This Policy
We may update this Privacy Policy from time to time. Changes will be posted on this page with an updated date.
27 June 2026 → 8 August 2026: section 7 corrected. The Microsoft Clarity masking mode was described as Strict; it was Balanced. Element-level masking has been applied to the calculator surfaces, and shared-result links no longer carry participant names in the address bar.