Privacy Policy

Last updated: 23 April 2026

1. Controller

The controller under the GDPR is:

René Zander Langer See 29A 15754 Heidesee Germany Email: [email protected] Phone: +49 156 78 43 65 34

2. Overview

I process personal data only to the extent necessary to provide a functioning website and to deliver my content and services. Legal bases are Art. 6(1)(a), (b), and (f) GDPR.

3. Hosting

The site is served via Cloudflare Pages (Cloudflare, Inc., 101 Townsend St, San Francisco, CA 94107, USA). Cloudflare processes connection data (IP address, timestamp, HTTP headers, referrer) for content delivery, DDoS protection, and security (Art. 6(1)(f) GDPR). Processing is based on the EU Standard Contractual Clauses. More: https://www.cloudflare.com/privacypolicy/.

4. Server log files

When you visit the site, the hosting provider automatically collects information (server log files) including:

  • IP address
  • date and time of request
  • URL accessed
  • user agent (browser / OS)
  • referrer URL

These data are used for delivery of the site and to maintain security (Art. 6(1)(f) GDPR) and are deleted or anonymized after a short period.

5. Cookies and local storage

No advertising cookies are used. Used only:

  • Language preference cookie (lang): stores your DE/EN choice. Lifetime: 1 year. Legal basis: Art. 6(1)(f) GDPR (functionally necessary).
  • Session storage: one-time attribution of a traffic source per browsing session.

6. Analytics: PostHog

For reach measurement I use PostHog (PostHog EU hosting, Porzellanhof 4, 1010 Vienna, Austria). PostHog captures pseudonymized data on page views, duration, browser, OS, and click interactions. IP addresses are truncated; no personal profiles are built.

Legal basis: Art. 6(1)(f) GDPR (legitimate interest in analyzing and improving my offering).

Data is processed in the EU. More: https://posthog.com/privacy.

Opt-out: you can object by using a tracker-blocking browser or blocking scripts in your browser settings.

7. Contact

7.1 Email and phone

If you contact me by email or phone, your data are stored for processing your request and for any follow-up (Art. 6(1)(b) or (f) GDPR).

7.2 Contact form (scoping / checklist)

If you use a form on this site, I process the data you provide (name, email, further details) to handle your request. Data is stored in Cloudflare KV (Europe). I additionally receive a notification via the Telegram Bot API (Telegram Messenger Inc.). I use Telegram only for internal notification; Telegram processes the data on its servers. Legal basis: Art. 6(1)(b) or (f) GDPR.

7.3 Spam protection: hCaptcha

To protect forms from automated submissions I use hCaptcha (Intuition Machines, Inc.). hCaptcha processes device and usage data to distinguish humans from bots. Legal basis: Art. 6(1)(f) GDPR. Details: https://www.hcaptcha.com/privacy.

7.4 Appointment booking: Cal.com

For online booking of conversations I use Cal.com (cal.com, c/o Cal.com, Inc.). On booking, name, email, and appointment details are transmitted to Cal.com. Legal basis: Art. 6(1)(b) GDPR. Details: https://cal.com/privacy.

The site contains links to external services (e.g. LinkedIn, GitHub, Hugging Face, dev.to). When you follow these links, information is transmitted to the respective operators. I have no influence over their data processing; please consult their privacy statements.

9. Your rights

You have the following rights vis-à-vis me as controller:

  • Access (Art. 15 GDPR)
  • Rectification (Art. 16 GDPR)
  • Erasure (Art. 17 GDPR)
  • Restriction of processing (Art. 18 GDPR)
  • Objection to processing (Art. 21 GDPR)
  • Data portability (Art. 20 GDPR)
  • Withdrawal of consent (Art. 7(3) GDPR)

To exercise your rights, an informal message to [email protected] is sufficient.

10. Right to lodge a complaint

You have the right to lodge a complaint with a data protection supervisory authority about the processing of your personal data. The competent authority for me is the Berlin Commissioner for Data Protection and Freedom of Information.

11. Currency of this policy

As my offering evolves or legal requirements change, this policy may need to be adjusted. The current version is always available on this page.