In short

• Controller: Gerhard Kanzler, Ahornweg 1, 83410 Laufen, Germany. Contact: tellstack@rz-solutions.dev.
• Stored data: account (email, name, passkey public key), sessions (hashed IP, browser string), feedback with optional email and technical metadata, billing counters, and — on AI plans — derived analysis kept separately from the raw message.
• Processors: Hetzner (hosting, Nuremberg, Germany), Stripe (payments), Resend (reply emails, invitations and account notices), OpenAI (AI plans only, feedback text without name or email), and — only if you turn on notifications — the push service of your own browser vendor (Google, Apple or Mozilla), which delivers an encrypted payload it cannot read.
• Retention: feedback stays until you delete it or close the account. Sessions, invitations, recovery grants, processed payment events and completed AI jobs expire on their own. Feedback itself never expires automatically.
• Cookies: two technically necessary cookies for signing in. No advertising cookies, no session recording — the analytics we do run needs no cookie either.
• Analytics: a self-hosted Umami instance on a server at Hetzner in Nuremberg — no data goes to an analytics vendor. No cookies, no IP addresses stored; a daily-rotating hash groups the requests of one visit and cannot be reversed. The hosted feedback forms under /f/ are deliberately not measured: those visitors are our customers' users, not ours. Browsers sending “Do Not Track” are not counted.
• Your rights: access, rectification, erasure, restriction, portability and objection under Art. 15–21 GDPR. Supervisory authority: BayLDA, Promenade 18, 91522 Ansbach, Germany.
• Invoices are kept for ten years — German commercial and tax law requires it. Everything else goes when you delete it.
• Resend and OpenAI also process in the US, on the EU Commission's standard contractual clauses. Without an AI plan nothing is sent to OpenAI at all.