Privacy Policy

Last updated: 25 October 2026

Who we are

Calculoco is made by Martin Šlechta, a sole trader in the Czech Republic, who is the controller of the data described here. Contact: hello@calculoco.com.

Data that stays on your device

Your lessons, mastery progress, streak, daily goal, settings and calculator history are stored on your iPhone (and passed to your own Apple Watch if you use the Watch app). We don't receive them. They're included in your device backups like any other app data, and deleting the app deletes them.

Anonymous usage statistics

To find out what works and what doesn't, the app sends anonymous usage signals to TelemetryDeck (TelemetryDeck GmbH, Germany, servers in the EU). For example: a lesson was finished with 80 % accuracy, the Sprint was played, the paywall was opened, the chosen language. Each signal also includes the app version, the operating system version, the device model and the country.

Signals are tied only to a random ID created on first launch, which TelemetryDeck hashes again so it can't be traced back to you or your device. We don't send your name, email, IP address, contacts, precise location or anything you type.

Anonymous learning statistics

To make the lessons better (which numbers are hardest, which exercises help people remember), the app may also send anonymous answers to our database at Supabase (servers in Frankfurt, Germany): which number was asked, whether the answer was right and how long it took. These records carry the same random ID and nothing that identifies you.

Speaking practice

The Speak mode uses your microphone and Apple's speech recognition to check what you said. The audio is processed by Apple, on your device or on Apple's servers, under Apple's privacy policy. Calculoco never records, stores or sends your voice anywhere else. The microphone is used only during a Speak round, and only if you allow it.

Purchases

Calculoco Pro is bought through Apple. Apple handles the payment; we never see your name, card or Apple ID. The app learns only whether Pro is active, and our statistics record the plan, price, currency and country of a purchase, anonymously.

Reminders

Daily reminders are scheduled on your device. No notification server and no personal data are involved.

Legal basis and retention

We process anonymous statistics on the basis of our legitimate interest in improving Calculoco (Article 6(1)(f) GDPR). Because they can't be linked to you, they're kept as long as they're useful for comparing trends over time.

Children

Calculoco is suitable for all ages. It collects no personal information from anyone, children included, and shows no ads.

Your rights

Under the GDPR you have the right to access, correct or delete personal data, to object to processing and to complain to a supervisory authority; in the Czech Republic that's the Office for Personal Data Protection (uoou.gov.cz). Because our data is anonymous, we usually can't tell which records are yours, but write to us and we'll help however we can.

Changes

If this policy changes, we'll update the date above and, for important changes, tell you in the app.