Privacy Policy

Last updated: April 2025. This policy applies to sudoku.by and all its language subdomains.

The short version: We collect only what we need to run the service. We do not sell your data. We do not use advertising cookies. You can request deletion of your account at any time.

1. Information We Collect

Account Data

When you create an account we collect your email address, a username you choose, and a password stored as a secure bcrypt hash. We never store your password in plain text.

Gameplay Data

We log puzzle completions, solving times, mistake counts, and scores. This data powers leaderboards, personal statistics, daily challenges, and competition scoring.

Technical Data

Standard server logs capture IP addresses, browser user agents, and request timestamps for security and performance monitoring. These logs are retained for 30 days and are not linked to your account for analytics purposes.

2. How We Use Your Information

To operate the service, manage your account, and display your scores
To send transactional emails: account verification, password resets, and competition notifications you opt into
To detect and prevent cheating in competitions
To improve puzzle generation, difficulty calibration, and platform performance

We do not use your data for advertising, profiling, or sale to third parties.

3. Cookies

We use a minimal set of essential cookies. No advertising or tracking cookies are used. See our Cookie Policy for the full list.

4. Data Sharing

We do not sell, rent, or trade personal data. We may share data only in the following circumstances:

Service providers: Hosting and email delivery providers operating under data processing agreements
Legal requirements: If required by applicable law or valid legal process

5. Data Retention

Account data is retained for as long as your account is active. Gameplay records (scores, times, leaderboard entries) associated with a deleted account are anonymised rather than deleted, to preserve leaderboard integrity. You may request full deletion by contacting us.

6. Your Rights

Depending on your jurisdiction you may have the right to access, correct, or delete your personal data, or to object to or restrict its processing. To exercise any of these rights, contact us at [email protected].

7. Security

We use HTTPS for all connections, bcrypt for password hashing, and CSRF protection on all form submissions. We take reasonable steps to protect your data, but no internet service can guarantee absolute security.

8. Changes to This Policy

We may update this policy from time to time. If material changes are made, we will notify registered users by email. Continued use of the service after the effective date constitutes acceptance of the revised policy.

9. Contact

For privacy questions or data requests: [email protected]