Privacy Policy — Chess Puzzle Vault

This policy explains what information Chess Puzzle Vault ("we", "us") collects when you use the site, why we collect it, and the choices you have. We collect as little as we need to run the service, and we do not sell your personal information.

1. Information we collect

We collect information in three ways: what you give us, what's generated by using the service, and what's collected automatically.

Account information — username, email address, and a securely hashed password when you register.
Puzzle activity — the puzzles you attempt, your solve times, accuracy, your rating history, streaks, and achievements. This is what makes the adaptive training and spaced repetition work.
Preferences — settings like board theme, piece set, and light/dark mode.
Technical data — your IP address (stored in hashed form, not in plain text), browser type, and basic device information, collected for security, abuse prevention, and aggregate usage statistics.
Messages you send us — the name, email, and message content you submit through the contact form.

2. How we use your information

To create and secure your account, and keep you signed in.
To calculate your puzzle rating, track progress, and schedule spaced-repetition reviews.
To operate the leaderboard and achievements, if you choose to participate.
To detect abuse — such as automated solving, rating manipulation, or scraping — and keep the platform fair for everyone.
To respond to support requests and contact-form messages.
To understand aggregate usage (e.g. which themes are most popular) so we can improve the platform. This analysis uses internal, first-party statistics — we do not sell or share this data with data brokers.

3. Cookies & local storage

We use a small number of strictly-necessary cookies to keep you signed in and to protect against cross-site request forgery. We also use your browser's local storage to remember display preferences, such as light/dark theme and board settings, entirely on your device. We do not use third-party advertising or cross-site tracking cookies of our own.

4. Advertising

To keep Chess Puzzle Vault free for everyone, some pages may display advertising served through Google AdSense. If enabled, Google and its partners may use cookies or similar technologies to serve ads based on your visits to this and other sites. Ads are never shown inside an active puzzle and never block the board or controls. You can learn more about, and opt out of, personalized advertising at Google Ads Settings.

5. How we protect your data

Passwords are never stored in plain text — they're hashed with Argon2id, a modern, memory-hard hashing algorithm. Data is stored on secured servers, access is restricted to what's operationally necessary, and all traffic to the site is encrypted in transit.

6. Data retention

We keep account and puzzle-history data for as long as your account is active, since it's what powers your rating and spaced-repetition schedule. If you delete your account, we remove your personal information within a reasonable period, except where we're required to retain limited records for security or legal reasons.

7. Your rights & choices

Wherever you're located, you can:

Access or update your account information at any time from your profile settings.
Request an export of your data.
Request deletion of your account and associated personal data.
Opt out of personalized advertising, as described above.

To exercise any of these rights, contact us and we'll respond as quickly as we can.

8. Children's privacy

Chess Puzzle Vault is intended for a general audience and is not directed at children under 13. We do not knowingly collect personal information from children under 13. If you believe a child has provided us with personal information, please contact us and we will remove it.

9. Changes to this policy

We may update this policy as the platform evolves. Material changes will be reflected by updating the "last updated" date above. Continued use of Chess Puzzle Vault after changes take effect constitutes acceptance of the revised policy.

10. Contact us

Questions about this policy or your data? Reach out through our contact page.