Privacy Policy
Last updated: November 8, 2026
Block Clarity Hub is committed to protecting your privacy. This policy explains what information we collect, how we use it, and your rights regarding your data.
Information We Collect
We collect minimal information necessary to provide our educational services:
Account Information
Your email address, stored in our own PostgreSQL database when you sign in. You sign in with a one-time email link or, where offered, with Google. If you use Google, we also receive and store your Google account email, name and profile picture URL, your Google account ID, and the OAuth access and ID tokens Google returns (kept in the accounts table). We do not ask for your address or phone number.
Learning Progress
Which sections you have marked complete. While you are signed in these are saved to our database against your account; they are also kept in your browser's local storage on the device you use.
Quiz Scores
The score and total from quizzes you complete while signed in, saved to our database against your account and also kept in your browser's local storage.
Watchlist
The coins you add to your watchlist while signed in, saved to our database against your account.
Newsletter
If you subscribe to the newsletter, the email address you give is stored in our database, together with the subscription status and the place on the site where you signed up.
Usage Analytics
Page view and interaction data collected by Google Analytics 4 (see Cookies below), used for aggregate page statistics to understand which content is most useful.
How We Use Your Information
- Progress tracking: To save and display your learning progress, quiz scores and watchlist while you are signed in
- Content improvement: Aggregate usage data helps us identify which topics need more coverage, better explanations, or updated information
- Service functionality: Authentication and session management to keep you signed in, and sending your sign-in link
We will never sell your data. Period. We do not share your information with advertisers or data brokers. The service providers listed below receive only what they need to do their job.
Third-Party Services
We use a limited number of third-party services to operate the site:
Google (sign-in)
Optional “Continue with Google” sign-in. If you choose it, Google tells us your account email, name, profile picture URL and account ID, as described above. We only accept a Google sign-in when Google reports the email address as verified.
Google Analytics
Google Analytics 4 is loaded on every page to measure page views and interactions. See Cookies below.
Resend
Email delivery. Your email address and the sign-in link are passed to Resend to send the one-time sign-in email.
PostgreSQL database
Accounts, sign-in records, progress, quiz scores and watchlists are stored in the site's own PostgreSQL database, not with a separate authentication vendor.
Error reporting
When the server hits an error, a report with the page address and the technical error details goes to our own self-hosted error tracker. Cookies and sign-in headers are removed from these reports, and they are not shared with anyone.
CoinGecko API
Market data for cryptocurrency prices and statistics. No user data is sent to CoinGecko — we only fetch public market data from their API.
Hetzner Cloud
Website hosting (Nuremberg, Germany). EU-based provider subject to GDPR. Subject to Hetzner's Privacy Policy.
Cloudflare
DNS, CDN, and security layer in front of our origin server. Cloudflare may process IP addresses and request metadata to serve cached content and block malicious traffic. Subject to Cloudflare's Privacy Policy.
Cookies
Sign-in cookies. When you sign in, the site sets a signed session cookie (a JWT) that is valid for 24 hours. Auth.js, the sign-in library we use, also sets small essential cookies (a CSRF token and a callback URL) on pages that are generated per visit, including the sign-in pages. These are needed for login to work.
Google Analytics cookies. Google Analytics 4 is loaded on every page and sets its own cookies in your browser. We use it for aggregate page statistics. These cookies are not required for the site to work. You can block them in your browser settings or with a tracking-protection extension.
We do not use advertising cookies.
Your Rights
You have the following rights regarding your data:
- Access: Request a copy of the data we hold about you
- Deletion: Request deletion of your account and the data stored against it
- Export: Request your data in a portable format
- Opt out: Browse the site without signing in; progress, quiz scores and watchlist are only saved to our database when you are signed in
Under GDPR (EU) and CCPA (California), you have additional rights including the right to rectification, erasure, data portability, and the right to object to processing. To exercise any of these rights, contact us at the email below.
Data Retention
Account data is retained for as long as your account is active. If you wish to remove the data associated with your account, email us at the address below and we will delete your account, learning progress, quiz scores, watchlist and sign-in records. Data kept in your browser's local storage stays on your device until you clear it.
Security
We take the security of your data seriously and implement appropriate technical measures:
- All data is encrypted in transit using HTTPS/TLS
- Sign-in uses single-use email links; the session cookie is signed and expires after 24 hours
- Progress, quiz scores and watchlist are read and written only for the signed-in account they belong to
Children
Block Clarity Hub is not directed at children under the age of 13. We do not knowingly collect personal information from children under 13. If we become aware that we have collected data from a child under 13, we will delete that information promptly. If you believe a child under 13 has provided us with personal data, please contact us immediately.
Changes to This Policy
We may update this privacy policy as needed to reflect changes in our practices, technology, or legal requirements. When we make changes, we will update the "Last updated" date at the top of this page. For significant changes that materially affect your rights, we will provide prominent notice on the site. We encourage you to review this policy periodically.
Contact
For any questions about this privacy policy or to exercise your data rights, contact us at:
You can also open an issue on our GitHub repository for transparency.