Privacy Policy

The short version

8ctoMath keeps each child's progress in a small file on your own device. It contains no advertising, no analytics and no tracking of any kind, and it needs no account and no internet connection to play. If you never sign in to Sync, nothing a child does in 8ctoMath ever leaves the device.

What is stored on the device

For each child you add, 8ctoMath stores one small file in the app's own private storage:

• the nickname typed in for that child, up to ten characters — a real first name is not needed, and a made-up one works just as well;
• the day the child was added;
• which kinds of calculations they practise and the level they have reached in each;
• which numbers they tend to get wrong, as a set of weights, so those calculations come back more often;
• their avatar, put together from the app's own pictures: a creature, a hat, a little extra, a backdrop and a colour;
• their pearls, the stickers they own, where each sticker is stuck in the book, and the stickers they have given to a brother or sister on the same device;
• the four-digit PIN a child may choose so that nobody else plays as them — optional, and a grown-up can take it off in the parents' area;
• how many questions they answered and how many were wrong, how many quizzes they finished, how long they practised and the levels they reached, per day, for their progress page, for up to 400 days of play;
• how long their last few quizzes took, which is what paces Brainy.

When a child is added, 8ctoMath also asks how old they are. The age only picks the kinds of calculations the first quiz asks and the level each one starts at, and is then forgotten: it is not stored.

Device settings — sound, music, voices, calm motion, language and the daily reminder's time — are stored separately in the same private area, together with whether the rules of the game have been shown, whether 8ctoMath+ has been bought, which account Sync belongs to while you are signed in, and a random label the app makes up for itself when it is installed, so that pearls and stickers earned on two devices add up correctly.

Apart from the age above, we ask for nothing about a child, and we do not store a birthday, an age, an email address, a photograph, a contact, a location, or anything else about them. No identifier of your device or of your advertising profile is read or stored.

What is not in the app

• No advertising.
• Nothing a child can buy: the one purchase, 8ctoMath+, sits behind the grown-ups' gate.
• No analytics or usage measurement, from us or anyone else.
• No advertising identifier, no fingerprinting, no profiling.
• No crash or performance reporting.
• No social network, no chat, and no contact with anyone beyond the children on the same device.
• No links out of the game, other than this page, an email link to us and Google Play's page for redeeming a code, all in the parents' area behind the grown-ups' gate.

8ctoMath+

8ctoMath+ is a one-time purchase, with no subscription, that opens every sticker, every sticker page and every part of the avatar, and includes Sync. It is bought through Google Play, behind the grown-ups' gate.

Google Play handles the payment under its own terms: we never see a name, an address or any payment details. The app asks Google Play whether 8ctoMath+ has been bought and keeps that answer on the device. When you are signed in to Sync, it also sends Google Play's reference for the purchase (the purchase token, which holds no name and no payment details) to our server in Zürich, which asks Google Play to confirm it before 8ctoMath+ is added to your account. Only a one-way fingerprint of that reference is stored, with your account, so that one purchase belongs to one account; the server also counts, for an hour at a time, how often an account has asked, to stop abuse. Codes for friends and family are redeemed on Google Play's own page.

Sync

Sync keeps a family's children the same on every device they play on, and keeps a copy of them in an account, so they survive a lost device. It is part of 8ctoMath+, it is off until you sign in in Parents → Sync, and the game is complete without it.

Signing in uses Firebase Authentication, with an email address and password or with your Google account; from a Google sign-in we receive the email address and display name of that account. Once you are signed in, the per-child data listed above, including the random label of each device that earned pearls or stickers for a child, is copied to Google Cloud Firestore, hosted in Zürich, Switzerland, one document per child, and kept up to date from then on. It is sent over an encrypted connection and stored under your account. As with any Firebase-backed app, Google records the IP address and user agent of these requests for sign-in security. To keep the account safe from anything that only pretends to be 8ctoMath, the app also asks Google Play to vouch that it is the genuine app (Firebase App Check with Play Integrity); Google handles that request under its own terms, and we receive only its yes or no.

When you sign in on a device that has children of its own, an empty account takes them all. An account that already has children takes this device's only if you choose them over its own, which are then removed from the account, and a child who has not played yet is left out of that choice. Children who are not taken stay on the device, where signing out brings them back.

Sync is used for nothing but keeping your devices in step and restoring them. It is never used to profile anyone, never sold, and never shared with a third party other than Google as the provider of the service above.

Cookies and tracking

8ctoMath uses no cookies, no advertising identifiers, no analytics and no tracking technologies. This website sets no cookies either. It is served by GitHub Pages, which — like any web server — records the IP address and user agent of each request in its own logs.

Children

8ctoMath is made for children, and is built to the standard that requires: no advertising, no analytics, no third-party tracking, nothing a child can buy, and no personal data collected about a child beyond the nickname typed in when they are added and the PIN they may choose. Everything that could matter to a parent — settings, levels, deleting a child or all the data, 8ctoMath+ and Sync — sits behind a gate that asks for a number written out in words to be typed in digits.

Because no contact details of a child are ever collected, we cannot and do not contact a child.

Data retention

Data on the device is kept until you delete it, and no longer than the app is installed: Parents → Danger zone → Delete all data removes every child and the settings at once, and uninstalling 8ctoMath removes the app's private storage, with every child's progress on that device. If you use Sync, deleting a child removes them from the account as well, and from every device signed in to it; deleting all the data while signed in does the same for every child. The fingerprint of a purchase stays with the account until the account is deleted or Google Play reports the purchase as refunded, which our server checks once a day.

Data sharing

We do not share personal data with anyone. If you sign in to Sync, the data described above is processed by Google as the operator of Firebase Authentication, Cloud Firestore and Cloud Functions, on our behalf and for no other purpose. A purchase of 8ctoMath+ is handled by Google Play under Google's own terms; our server asks Google Play only whether a purchase is valid.

Your rights

Since a child's data lives on your device, you control it directly: Parents → Children → Delete removes a child and everything belonging to them, and Parents → Danger zone → Delete all data removes all of it at once, from the account as well while you are signed in. If you have used Sync, deleting a child also removes them from the account, and Parents → Danger zone → Delete account removes the account and everything stored with it for good. The Data Deletion Policy sets this out step by step.

You may also write to us to ask what is stored about you, to receive a copy, or to have it deleted.

Changes to this policy

If we change what 8ctoMath collects, we will update this page and change the date at the top.

Contact

For questions or requests, email hi@8cto.net.