Privacy Policy

This Privacy Policy explains how CalculusDX ("we", "us") handles your information when you use our website and online course (the "Service").

1. Information we collect

• Account information: your email address, which you give us to sign up and receive sign-in links.
• Consent records: the date you accepted our Terms and this Policy, and whether you chose to receive marketing emails.
• Learning progress: lessons completed, practice answers, and study plans, which may be stored in your browser or your account.
• Technical data: basic device, browser, and usage information (such as pages visited and error logs) collected automatically to keep the Service running and secure.

2. How we use your information

• To create and secure your account and send you sign-in links.
• To provide the course and save your progress.
• To send essential service messages (for example, account or policy changes).
• Only if you opt in: to send newsletters, offers, and news about new courses and features.
• To understand and improve the Service, and to prevent abuse.

3. Marketing emails

Marketing emails are optional and off by default. You can opt in when you sign up, and you can unsubscribe at any time using the link in any marketing email or from your account page. Opting out does not affect your access to the course.

4. Legal bases (EEA/UK users)

We process your data to perform our contract with you (providing the Service), on the basis of your consent (marketing emails), and for our legitimate interests (security and improving the Service).

5. Sharing

We do not sell your personal information. We share it only with service providers that help us run the Service (such as hosting, database, and email delivery providers), under agreements that require them to protect it, or when required by law.

6. Data retention

We keep your account data while your account is active. If you delete your account, we delete or anonymize your personal data within a reasonable time, unless we must keep it to meet legal obligations.

7. Your rights

Depending on where you live, you may have the right to access, correct, delete, or export your data, and to withdraw consent or object to processing. You can update your email or delete your account on your account page.

8. Children

The Service is intended for users aged 13 and older. If you are under the age of majority where you live, please use the Service with a parent or guardian's permission. We do not knowingly collect data from children under 13.

9. Security

We use reasonable technical and organizational measures to protect your information, including encrypted connections and passwordless sign-in. No system is completely secure.

10. Changes

We may update this Policy. If changes are significant, we will notify you by email or on the site. The "Last updated" date shows the latest version.