Mental Math works without an account: you never give us a name, an email address or a password. This policy explains what the app and this website store anyway, which services help us run them, and what you can do about it. It covers the Mental Math app for iPhone and iPad, its optional server features and the website mental-math.app.
Who is responsible
The controller is COFFEE BYTES, UNIPESSOAL LDA, Avenida Infante, No. 8, Edifício Executivo, 2. K, 9000-015 Funchal, Madeira, Portugal, email contact@coffee-bytes.io (“we”). Write to that address for every question in this policy.
What the app stores on your device
- Profile: a random identifier created on first launch, the goal you picked during onboarding, and your settings (reminders, sounds, card layout, Pro status).
- Practice history: every Bootcamp session and Arcade run with its operation, level, mode, start and end time, each task with your answer and response time, score, Success Rate, Average Response Time, points and streak.
- Progress: your Skill Rating and its history, level and times-table progress, daily summaries, personal bests and missed facts for review.
This data lives in a database inside the app's own container on your device, where the widget reads it too. Finished sessions are also added to the device's Spotlight index so you can find them from the Home Screen search; that index never leaves the device. Deleting the app deletes all of this. Settings → Delete Account deletes it too and resets the app.
iCloud backup
If iCloud is turned on for Mental Math, your practice history and progress are mirrored to your private iCloud database so that your devices stay in sync and a new device can restore them. That database belongs to your Apple ID; Apple processes it under its own privacy policy and we cannot read it. Turn iCloud off for Mental Math in the system settings to stop this.
Our server: session summaries and reminders
The app talks to a server we run so that your results are not lost with the device and so that practice reminders can be sent even when the app is closed. There is still no account: on first contact your device proves through Apple's App Attest that it is a genuine installation of Mental Math, and the server issues an anonymous installation identity. The server then stores, for that installation:
- a summary of every finished session: operation, level, mode, whether it was timed, start and end time, duration, number of attempted, correct and incorrect tasks, score, Success Rate, Average Response Time (overall, correct and incorrect), points earned and your random profile identifier. Individual tasks and answers stay on the device.
- the push notification token of your iPhone or iPad, if you allowed notifications, so that practice reminders can be delivered, together with the reminder times you set.
The server runs on Hetzner infrastructure in the European Union (Hetzner privacy policy). Its access logs contain IP addresses for security purposes and are kept for up to 30 days. Legal basis: performance of the service you asked for (Art. 6(1)(b) GDPR) and our legitimate interest in keeping it secure and working (Art. 6(1)(f) GDPR). Settings → Delete Account deletes the installation and everything stored for it on the server, and withdraws the notification token.
Usage analytics
To understand which parts of Mental Math are used and where people get stuck, the app sends usage events to PostHog (privacy policy): which screens are opened, which buttons are tapped, that a session started or ended, its mode and result, and your Pro status. Events carry your random profile identifier, the app version, device model, operating system version and language; they contain no name, email address or individual answers. We do not use these events for advertising, and the app does not use Apple's tracking framework. Legal basis is our legitimate interest in improving the app (Art. 6(1)(f) GDPR).
Crash reports
If the app crashes or hits an unexpected error, a report goes to Sentry in its European Union data region (privacy policy). A report contains the technical state of the app at that moment: stack trace, app version, device model, operating system version, free memory and the last log lines, under the same random profile identifier. Legal basis is our legitimate interest in keeping the app working (Art. 6(1)(f) GDPR).
Purchases
Mental Math Pro is sold through Apple's App Store under Apple's terms and privacy policy. To check what you bought and to unlock Pro on all your devices, the app uses RevenueCat (privacy policy), which receives the App Store receipt, your random profile identifier, device type and app version. Apple does not give us your name, address or payment details. If you bought a Mental Math Pro subscription in an earlier version, RevenueCat also tracks that subscription's status.
Advertising
The free version of Mental Math shows interstitial ads between sessions, served by Google AdMob (Google privacy policy). To select, deliver and measure ads, Google and its advertising partners process your IP address, device information and, where you allow it in iOS, your device's advertising identifier. We do not request permission to track you across other companies' apps, and we never pass your practice data to Google. You can limit ad personalisation under iOS Settings → Privacy & Security → Apple Advertising and Tracking. Mental Math Pro removes all ads.
Game Center
If you are signed in to Game Center, your Arcade scores and achievements are posted to Game Center leaderboards and shown to you and your Game Center friends under your Game Center profile. Apple processes this under its own privacy policy; we receive no Game Center identity and cannot use it to recognise you. Sign out of Game Center in the system settings to stop this.
Feedback
Settings → Feedback opens a feedback board provided by UserJot (privacy policy). What you write there, any email address you choose to leave and your random profile identifier are stored by UserJot so that we can read and answer your feedback. Legal basis is your consent, given by sending the feedback (Art. 6(1)(a) GDPR).
Notifications
Daily practice reminders are scheduled on your device and, when you allowed notifications, delivered through Apple's push service as described above. Turn them off in the app's settings or in iOS Settings → Notifications.
This website
- Hosting: mental-math.app is served by Cloudflare, Inc. (privacy policy). Cloudflare processes the IP address and request details of every visit to deliver the site and protect it from abuse. We run no analytics or advertising scripts on this site.
- Preferences: choosing a language sets a cookie named
mm-lang; choosing a theme and playing the browser game storemm-themeandmm-try-bestin your browser. They exist only to remember your choice and your best score, and nothing in them is sent to us. - Contact form: your name, email address, topic and message, together with the country the request came from and your browser's identifier, are stored with Cloudflare for up to one year so that we can answer you. Legal basis is your consent (Art. 6(1)(a) GDPR), which you can withdraw by writing to us.
Your rights
Under the GDPR you may ask us to:
- confirm whether we hold personal data about you and give you a copy (access);
- correct inaccurate data (rectification);
- delete your data (erasure);
- restrict how we process it, or object to processing based on legitimate interest;
- receive the data you provided in a portable format;
- withdraw a consent at any time, without affecting what was done before.
Because the app identifies you only by a random identifier, the fastest way to delete everything we hold is Settings → Delete Account in the app. For everything else, write to contact@coffee-bytes.io; because the server knows you only by a random identifier, tell us roughly when you installed the app and, for the feedback board or the contact form, the email address you used, so that we can find your data. We answer within one month. You also have the right to lodge a complaint with a supervisory authority, in Portugal the Comissão Nacional de Proteção de Dados (CNPD), or with the authority of the country you live in. California residents have corresponding rights under the CCPA; we do not sell personal data.
Children
Mental Math asks for no account and no personal details. It is made for students and adults and is not directed at children under 13. We do not knowingly collect personal data from children; if you believe a child has sent us personal data through the feedback board or the contact form, write to us and we will delete it.
Changes
We will update this policy when the app or the services change, and show the date of the last change at the top. Material changes to how server data is processed will also be announced in the app.