We keep very little.
No ads, no trackers, no third-party analytics. No email address: Sign in with Apple only shares your name, and only if you sign in and choose to share it. Last updated 13 October 2026.
Who is responsible
Eudaimonia Tech Srl, company number J40/8792/2023, VAT code RO48149202, registered at Str. Opanez nr. 7, bl. 73, sc. 2, ap. 39, Bucharest, Romania, is the controller of your data in Lemma and on lemma.day. Write to [email protected] for anything in this policy.
What we keep, and why
| What | Why |
|---|---|
| A random player ID | Created on first launch, with no email or phone number, to keep your notebook and sequence. |
| Your profile | A display name if you give one, your choice about showing it on the global board (off unless you turn it on), your time zone, your reminder time and smart-reminder choice, when you last opened the app (so reminders can back off), and which onboarding lessons you finished. |
| Your solves | Lemma number, daily or archive, date, time, corrections, hints and the log of moves, to rank fairly and to check that a solve is valid. |
| Your progress | Sequence and best sequence, freezes held, lemmas proven and theorems. |
| Your circles | The circles you create or join, their names and invite codes, who is in them and when you joined. |
| Reminder token and log | Your device's push token, so we can send the reminder you asked for, and a record of when a reminder was sent and opened, to avoid sending twice. |
| Lemma Plus status | Which plan you hold, its expiry and whether it is shared through Family Sharing, passed on by Apple. We never see your card or payment details. |
| Product events | A short first-party log of what happens in the app (an event name, a few properties and the time) so we can find bugs and see what is used. It goes to our own database and nowhere else. |
What other people see
- Members of a circle see your name in that circle and your times, never your numbers.
- The global board shows your name only if you turned that on. Otherwise you appear without one.
- A share link you send carries your time and the order of your proof inside the link itself. It is read in the viewer's browser and is never sent to our server.
Sign in with Apple
If you sign in, Apple gives us a private identifier and, if you choose to share it, your name. We do not ask for your email address. Apple handles the sign-in under its own privacy policy.
Where it is kept, and who processes it
Your data is stored in a Supabase database hosted in Frankfurt, Germany. Supabase also keeps request logs, including IP addresses, for the app's server calls and sign-ins, and for the one call the website's invitation page makes to show a circle's name and its creator's name (so a visitor's IP address reaches Supabase from the website too), as Cloudflare does for the website. Our processors are Supabase (database, sign-in and server functions) and Apple (Sign in with Apple, App Store billing and the push notification service). For the website, lemma.day, the processor is Cloudflare, which hosts the pages and keeps the request logs a web host keeps, including visitors' IP addresses. The website sets no cookies and runs no analytics. Where data leaves the European Economic Area, it is covered by standard contractual clauses or an equivalent safeguard. Your notebook is also kept on your phone, and deleting the app removes that copy.
How long we keep it
Until you delete your account. In the app, open Settings, then Delete account: your solves, progress, circles and settings are removed from our server at once. Routine backups kept by our host age out on their own schedule and are not restored into live data. Purchase records stay with Apple under Apple's own terms.
On what basis
- To run the game you asked for: the player ID, solves, progress, circles and Lemma Plus status (performance of a contract).
- To keep boards fair and the service working: solve checks and product events (legitimate interests).
- For reminders and for showing your name on the global board: your consent, which you can withdraw in Settings or in your iPhone's notification settings.
Your rights
Under the GDPR you may ask for access to your data, a copy of it, correction, deletion, restriction or to object. We send a copy within 30 days of your request. Deletion is in the app, under Settings. If you are unhappy with how we handle your data, you may complain to the Romanian data protection authority, ANSPDCP (dataprotection.ro), or to the authority in your own country.
Children
Lemma is not aimed at children. It keeps no data beyond what is listed above, and it shows no ads.
Changes
If we change this policy in a way that matters, we update the date above and tell you in the app.