Privacy Policy

Last updated: October 29, 2026

1. Data Controller

Jakub Lasak Consulting
Aleja "Solidarnosci" 68/121, 00-240 Warszawa, Poland
NIP: 5214080890 | REGON: 529336199
Contact: hi@dataengineer.wiki

2. What Data We Collect

  • Account data: email address (when you create an account via Supabase authentication)
  • Usage data: pages visited, content progress (checkbox states), timestamps
  • Purchase data: email address and product access records (when you purchase via Stripe)
  • Subscription data: Substack subscription status and lifecycle events
  • Site measurement: anonymous first-party counts of visits, pages viewed and buy-button clicks, tied to a random ID in your browser's local storage, not to your name or email. If you sign in or buy, the traffic source that brought you (for example "linkedin" and the post's campaign tag) is stored with your account or purchase, so we know which channels bring customers. No cookies, no third parties
  • Error reports: when the site fails in your browser, technical error data (error message, stack trace, browser and operating system, the page path without its query string) is sent to Sentry so we can fix it. Your IP address, name and email are not sent

3. Legal Basis for Processing (GDPR Art. 6)

  • Contract performance: account creation, content delivery, purchase fulfillment
  • Legitimate interest: service improvement, security, anonymous first-party site measurement, error reports
  • Legal obligation: retention of purchase and tax records as required by Polish law

4. How We Use Your Data

  • To provide and maintain the service
  • To process purchases, send confirmation emails, and manage access to paid content
  • To track your learning progress (checkboxes, page views)
  • To diagnose and fix technical errors
  • To measure which pages and channels work, from the anonymous site measurement above

5. Data Processors (Sub-processors)

  • Supabase (US/EU) - authentication, database, user data storage
  • Stripe (US) - payment processing
  • Make.com (EU) - purchase fulfillment automation (email delivery, access provisioning)
  • Resend (US) - transactional email delivery
  • Cloudflare (US) - hosting, CDN, DDoS protection
  • Substack (US) - newsletter and subscription management
  • Sentry (US) - error reports

6. Cookies and Local Storage

We use no advertising or third-party analytics cookies, so there is no cookie banner.

Essential:

  • Supabase session tokens (authentication)

First-party measurement (no cookies):

  • A random visit ID and the traffic source of your first and latest visit (local storage), used only for the anonymous site measurement above

7. Data Retention

  • Account data: retained until you delete your account
  • Progress data: retained until you delete your account
  • Purchase records: retained for 5 years (tax/legal obligations)
  • Site measurement data: kept indefinitely to compare trends over time; it holds no name or email, only a random browser ID
  • Error reports: automatically deleted after 90 days

8. Your Rights Under GDPR

You have the right to:

  • Access your personal data
  • Rectify inaccurate data
  • Erase your data ("right to be forgotten")
  • Restrict processing
  • Data portability
  • Object to processing
  • Withdraw consent at any time

To exercise these rights, email hi@dataengineer.wiki.

You also have the right to lodge a complaint with the Polish supervisory authority:
Urzad Ochrony Danych Osobowych (UODO)
ul. Stawki 2, 00-193 Warszawa
https://uodo.gov.pl

9. Children's Privacy

Our service is not directed at children under the age of 16. We do not knowingly collect personal data from children under 16. If you believe we have collected data from a child, please contact us at hi@dataengineer.wiki and we will delete it promptly.

10. Automated Decision-Making

We do not use automated decision-making or profiling that produces legal effects or similarly significantly affects you.

11. International Data Transfers

Some of our processors are based in the United States. These transfers are protected by Standard Contractual Clauses (SCCs) approved by the European Commission, and the processors' compliance with applicable data protection frameworks.

12. Data Security

We implement appropriate technical and organizational measures to protect your personal data, including encrypted connections (HTTPS), access controls, and secure authentication.

13. Changes to This Policy

We may update this policy from time to time. We will notify you of significant changes by posting a notice on our website. Continued use after changes constitutes acceptance.

14. Contact

For any questions about this privacy policy or your personal data:
Jakub Lasak Consulting
Email: hi@dataengineer.wiki

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