Privacy policy

Last updated: 16 September 2026

CalcuBoss is a mental maths app for children aged 6 to 11. It is designed to use as little data as possible: you can try it without an account, the free parent account only asks for an email address, and payment for the Premium family subscription is handled by Stripe. This page explains, in plain language, what is stored, why, for how long, and how to delete it.

1. Who is responsible?

CalcuBoss is published by ICRAFT, a French simplified joint-stock company (SAS) with a share capital of €200, 58 rue de Monceau, 75008 Paris, France, registered with the Paris Trade and Companies Register under number 992314237. ICRAFT is the controller of the data described here (see the legal notice).

For any question about this policy or your data, write to us using the contact form.

2. What CalcuBoss does not do

• No advertising, and no advertising cookies or pixels.
• No selling, renting or sharing of data.
• No third-party analytics tools (such as Google Analytics): CalcuBoss measures its own audience (section 7).
• No scripts, fonts or images loaded from other websites: everything is served by calcuboss.com.
• Children are never asked for an email address.
• No advertising profiling.

3. Data stored on the device

So that children can pick up where they left off, CalcuBoss stores the following in the browser’s local storage (localStorage, under the key calcuboss):

• profiles: the nickname or first name chosen, avatar, grade and theme;
• the rewards set by parents (text and goal); they are never sent to the class;
• stars, points, trophies and day streaks;
• answer statistics: facts mastered or to review, response times and play time;
• app settings (language, voice, sounds, statistics…).

The app also stores, under the key calcuboss-anon, a random device identifier, used only for usage statistics (section 7).

Without an account, profiles and progress stay on the device: they are not sent to any server. Only the usage statistics described in section 7 are sent, unless you turn them off.

In the Parents’ area you can export progress to a file at any time, reset a profile or delete it. Clearing the site’s browsing data (or uninstalling the app) deletes the information stored on the device: without an account, remember to export progress first.

To work offline, the browser also keeps a copy of the app’s files (text, images, code). This cache contains no personal data.

4. The parent account

The parent account is free. It belongs to a parent or another adult, who manages the children’s profiles. It backs up progress, syncs it between your devices and gives access to the Parents’ area. The optional Premium family subscription also unlocks the whole path and all game modes (see below).

There is no password: you enter your email address, receive a 6-digit code sent by CalcuBoss, and you are signed in. The code is only valid for a limited time, the number of attempts is limited, and it is only stored as a hash (never in plain text).

Your email address is used to sign you in and, if needed, to answer your requests about the account. It is never used for advertising or shared with anyone other than our processor.

Data

Email address, language, dates the account was created, last signed in and last active; temporary sign-in code (as a hash).

Purposes

Creating and managing the account, signing you in, sending sign-in codes, protecting sign-in against abuse, answering your requests.

Legal basis

Performance of a contract, that is, providing the service you request by creating the account (Article 6(1)(b) GDPR); legitimate interest in securing sign-in (Article 6(1)(f)).

Retention

Until the account is deleted. An account that has been inactive for 3 years is deleted. Sign-in codes are only used until they are entered or expire.

Recipients

Authorised ICRAFT staff; Cloudflare, as processor (hosting, Cloudflare D1 database); Resend, as processor (sending sign-in codes by email).

The Premium family subscription

Premium family is an optional monthly or yearly subscription, described in the terms of sale and use. Payment takes place on the secure page of Stripe, our payment provider: card details are entered with Stripe and processed by Stripe only. CalcuBoss never sees or stores the card number.

Data

The account’s email address; subscription status and dates (renewal date, cancellation, renewal reminder); customer and subscription identifiers assigned by Stripe. Card details are collected and processed by Stripe only.

Purposes

Managing the subscription (sign-up, renewal, cancellation), issuing invoices, sending the reminder before each renewal, handling refund requests; for Stripe, securing payments and preventing fraud.

Legal basis

Performance of a contract (Article 6(1)(b) GDPR); legal obligation to keep accounting records (Article 6(1)(c)).

Retention

As long as the account exists. Invoices and accounting records are kept for 10 years, as required by law (Article L123-22 of the French Commercial Code).

Recipients

Authorised ICRAFT staff; Stripe Payments Europe, Ltd., payment service provider, acting as an independent controller for payment data (see Stripe’s privacy policy); Cloudflare, as processor (hosting and database); Resend, as processor (sending reminder emails).

5. Backing up and syncing progress

When you are signed in, children’s profiles and progress are stored on the account, so that they are backed up and available on every device where you sign in.

• They are stored with Cloudflare, in a Cloudflare D1 database with a “Western Europe” location hint.
• They are not end-to-end encrypted: Cloudflare encrypts the data stored on its disks, and only authorised ICRAFT staff can access it, for example to help you if something goes wrong.
• Deleting the account from the Parents’ area erases this copy of the progress and the sign-in sessions.

Data

Profiles (nickname, avatar, grade, theme) and progress (stars, points, trophies, answer statistics).

Purposes

Backing up progress, syncing it between your devices and showing the Parents’ area.

Legal basis

Performance of a contract (Article 6(1)(b) GDPR).

Retention

Until the profile or the account is deleted (an account that has been inactive for 3 years is deleted).

Recipients

Authorised ICRAFT staff; Cloudflare, as processor (Cloudflare D1 database).

6. The sign-in cookie

CalcuBoss uses a single cookie. There are no advertising cookies, no third-party cookies and no other advertising trackers.

Name

cb_session, set by calcuboss.com when you sign in.

Purpose

Keeping you signed in to the account. On the server, only a hash of this session token is stored.

Properties

HttpOnly (cannot be read by scripts on the page) and Secure (only sent over HTTPS).

Lifetime

6 months, or until you sign out or delete the account.

Consent

Not required: this cookie is strictly necessary for the service you request (Article 82 of the French Data Protection Act). That is why there is no consent banner.

7. Usage statistics

To understand how the app is used and improve it (for example, to spot a level that is too hard), CalcuBoss measures its own audience, with no third-party tool.

• The app creates a random device identifier (calcuboss-anon, in local storage) and sends usage events to calcuboss.com/api/events. This identifier is automatically renewed every 13 months.
• These events are: app opened (installed app or browser, language, signed in or not); child profile created (grade, theme); game finished (type of game, grade, level, number of questions and correct answers, duration, stars, points); placement test result; locked content reached; use of certain features (handwriting recognition, microphone, online voice, installation).
• They never contain names, email addresses or free text. CalcuBoss does not store IP addresses.
• These events are never linked to your account: they stay anonymous, even when you are signed in.
• They are used to produce aggregated statistics (active devices, games played, success rate per level…). They are not used for advertising or to follow you on other websites, and they are not shared with anyone.
• You can turn them off at any time in the app settings: “Anonymous statistics” (« Statistiques anonymes »). No more events are then sent from that device.

Data

Random device identifier (renewed every 13 months), the usage events described above, date and time. No account identifier.

Purposes

Audience measurement and aggregated statistics to improve the app.

Legal basis

ICRAFT’s legitimate interest in measuring its app’s audience and improving it (Article 6(1)(f) GDPR). You can object by turning off “Anonymous statistics”.

Retention

13 months, then deleted.

Recipients

Authorised ICRAFT staff; Cloudflare, as processor (hosting and database).

8. Reading aloud and the CalcuBoss voice

Questions and instructions can be read aloud in two ways.

The device’s voice

It uses the speech-synthesis voices of the device or browser (the browser’s “Web Speech” feature) and remains available offline. CalcuBoss itself then sends no text, but some of these voices are online services:

• Microsoft Edge “Natural” or “Online” voices: the text being read (for example “7 times 8”) is processed by Microsoft;
• Google voices in Chrome: the text being read is processed by Google;
• voices installed on the device (iPad, iPhone, many Android voices, offline Windows or macOS voices): everything happens on the device.

The CalcuBoss voice (optional)

This is a high-quality online voice. When it is used, the text of the question (for example “7 times 8”) is sent to calcuboss.com, which turns it into speech with Cloudflare Workers AI. This text contains no personal data. Offline, the device’s voice takes over.

In CalcuBoss settings you can choose the voice or turn off automatic reading of questions.

9. Answering out loud and handwriting recognition

The “answer out loud” option is optional. If you turn it on, the browser asks for permission to use the microphone, then uses its own speech recognition:

• in Chrome and Edge, the audio may be sent to Google or Microsoft for transcription;
• in Safari, transcription is handled by Apple, on the device or on Apple’s servers depending on the model.

CalcuBoss records no audio: only the recognised number is used to check the answer, and it is then discarded.

Reading handwriting on the whiteboard (✍️ button) happens entirely on the device: no drawing is sent or kept.

10. The Grand challenge leaderboard

At the end of each grade, the child can take on the Grand challenge. Their score may appear in a worldwide leaderboard and in their country’s leaderboard. Taking part is off by default: a parent must switch it on in the Parents area and choose the nickname that is shown.

Data

The nickname chosen by the parent (never the e‑mail address, never a surname, never a school), the score and how long the game took, the grade, the country code derived by our host when the score is sent, and a fingerprint of the device’s local token so the child can update their own score. No IP address is stored and no location data more precise than the country is used.

Purposes

Showing a monthly worldwide and per-country leaderboard to encourage the child; moderating inappropriate nicknames.

Legal basis

The parent’s consent (Article 6.1.a GDPR), given in the Parents area and withdrawable at any time.

Retention

13 months at most, then automatic deletion. The leaderboard resets every month.

Withdrawal

The “Leave the leaderboard” button in the Parents area deletes the submitted score straight away.

Pupils signed in with a class code never take part in this leaderboard: their data belongs to the school (see section 13).

11. The contact form

To get in touch, CalcuBoss offers a contact form rather than an email address displayed on the website, which keeps spam down.

Data

Your email address, the chosen subject, your message, the language and the date sent. To limit abuse, a hashed form of the IP address, which changes every day, is also kept for 48 hours and then erased.

Purposes

Replying to your message and handling your request; protecting the form against abuse.

Legal basis

ICRAFT’s legitimate interest in replying to people who contact it and protecting its service (Article 6(1)(f) GDPR).

Retention

1 year after sending, then deleted.

Recipients

Authorised ICRAFT staff; Cloudflare, as processor (hosting and database); Resend, as processor (forwarding messages to the team by email).

12. Recipients, hosting and transfers outside the European Union

Your data is only accessible to authorised ICRAFT staff, to its processors Cloudflare and Resend and, for subscription payments, to Stripe. Our host is:

Cloudflare acts on behalf of ICRAFT (Article 28 GDPR) for:

• hosting and delivering the website and app, and protecting them against attacks;
• the Cloudflare D1 database (accounts and subscriptions, profiles and progress, usage statistics, classes and pupils, contact form messages);
• Cloudflare Workers AI, for the CalcuBoss voice.

Like any host, Cloudflare processes technical connection data (IP address, browser type, pages requested) to deliver the site and protect it, in particular by limiting the number of requests per IP address. CalcuBoss does not store these IP addresses in plain form in its databases (the contact form only keeps a temporary hash, see section 11) and does not use them to measure its audience. Legal basis: legitimate interest in providing a reliable and secure service (Article 6(1)(f) GDPR).

As Cloudflare is a US company, data may be processed outside the European Union, including when the database is located in Europe. These transfers are safeguarded: Cloudflare is certified under the EU–U.S. Data Privacy Framework and relies on the European Commission’s Standard Contractual Clauses. See Cloudflare’s privacy policy.

Resend, Inc. (United States) also acts on behalf of ICRAFT (Article 28 GDPR): it sends CalcuBoss emails (sign-in codes, reminders before the subscription renews) and forwards contact form messages to the team. Emails are processed in its European region; any transfers outside the European Union are safeguarded by the European Commission’s Standard Contractual Clauses.

Stripe Payments Europe, Ltd. (Ireland) processes payments for the Premium family subscription as an independent controller: it receives the account’s email address and card details, and uses them under its own privacy policy, in particular to secure payments and prevent fraud.

Data is not disclosed to any other organisation, unless required by law (for example, at the request of a judicial authority).

13. Children

CalcuBoss is designed for children aged 6 to 11, but the account is created by a parent or legal guardian (or another responsible adult), with their own email address. Children never have to provide an email address.

We recommend choosing a nickname with the child rather than their real first name. The Parents’ area is protected by a question meant for adults.

If you believe a child has created an account without their parents’ agreement, write to us using the contact form and we will delete it.

Pupils in a class (teacher space)

A teacher can create a class and add their pupils. Pupils sign in with the class code and a picture code (three pictures), with no email address or password.

Data

The nickname chosen by the teacher (a first name or a nickname, never a surname), the avatar, the picture code, progress in the app (stars, levels, success per skill, play time) and first-try mistakes (the calculation, the answer given and the type of mistake). No email address or contact details of the pupil.

Purposes

Letting pupils find their progress on class devices and at home; letting the teacher follow the class, spot difficulties and set homework.

Responsibilities

For pupils’ data, the school (or the authority it depends on) is the controller; ICRAFT acts as its processor (Article 28 GDPR) and uses this data for no other purpose: no advertising, no selling, no profiling.

Retention

As long as the class exists. The teacher can delete a pupil or the class at any time; an archived class is deleted one year after being archived. A device unused for more than a year is signed out.

Recipients

The class teacher; authorised ICRAFT staff; Cloudflare, as processor (hosting and database).

Parents who wish to exercise their rights over their child’s data can contact the teacher or the school, or write to us using the contact form.

14. Security

• All communication uses an encrypted connection (HTTPS).
• Card payments take place on Stripe’s secure page: no card number goes through CalcuBoss servers.
• No password to steal: sign-in codes and session tokens are only stored as hashes, and the number of attempts is limited.
• Data stored with Cloudflare is encrypted on its disks; it is not end-to-end encrypted.
• Access to the data is restricted to authorised ICRAFT staff.

15. Your rights

The General Data Protection Regulation (GDPR) and the French Data Protection Act give you the rights of access, rectification, erasure, restriction, portability and objection, as well as the right to give instructions on what happens to your data after your death. Most of these rights can be exercised directly in the app:

• access and portability: export the data from the Parents’ area;
• rectification: change the nickname, avatar, grade or theme in the settings;
• erasure: delete a profile, or delete the account from the Parents’ area, which stops any subscription and erases the copy of the progress and the sign-in sessions (invoices are kept for 10 years, as required by law); on the device, clear the site’s data in the browser;
• objection to statistics: turn off “Anonymous statistics” in the app settings.

For any other request (for example, changing the account’s email address), write to us using the contact form. To protect your data, we may ask you to confirm that the request comes from the account’s email address. We reply within one month.

You can also lodge a complaint with the French data protection authority, the CNIL: www.cnil.fr.

16. Changes

If this policy changes, for example when a new feature is added, this page will be updated along with the date above. If the change is significant, we will let you know in the app. This English version is provided for convenience; the French version prevails.