As of: October 2026 — the web version has been free since 2 October 2026. The terms and the right-of-withdrawal notice of the former paid access are therefore obsolete and have been removed.
Note on this translation. This English text is provided for your convenience only. The legally binding version is the German original (steuertool-rechtliches.html). In the event of any discrepancy, the German version prevails.
This notice supplements the general privacy information of alien-investor.org.
The most important thing first: your transaction data never leaves your browser. The App processes your CSV files entirely locally on your device. There is no upload, no storage and no transmission of your financial data to us or to third parties. This is not a mere promise but built that way by design — the calculation core is open source and verifiable. All technical components too (Python runtime, fonts, exchange-rate tables) are loaded from our own server — no third-party CDNs, no exchange-rate service. Using the App creates no connection to third parties.
1. Accessing the App (legal basis: Art. 6(1)(f) GDPR — legitimate interest in secure operation) — When you open the App, our server (location: Germany, Hetzner Online GmbH) processes technically necessary connection data (IP address, time, file requested) in server logs. Log data is automatically deleted after a short time. There are no user accounts and no personal access links.
2. Local storage on your device — The App stores in your browser's localStorage only the colour scheme and the chosen language. This data stays on your device and can be deleted by you at any time via your browser settings. No cookies are set; there is no analytics.
3. Exchange rates — Purchases in CHF or USD are converted using the bundled ECB reference rates that ship with the App as a table. No exchange-rate lookup at a third party takes place — not even for date or currency.
4. Bug report (voluntary) — The "Report a bug" button opens your e-mail program with a prepared text (detected file types and your description). File names or contents of your files are not inserted. Only what you send yourself is transmitted; we process the e-mail to answer your request (Art. 6(1)(f) GDPR).
5. Android app and Linux desktop app — The app editions (since October 2026) contain the calculation core, runtime and rate tables and make no connection to our server or to third parties after installation; the Android app has no internet permission, the Flatpak no network permission. Language and theme are stored locally on your device. When you download the app, our server processes the connection data as under 1; if you get it via GitHub or the Zapstore, their terms apply. Links in the app (website, GitHub, e-mail) open your browser or e-mail program outside the app.
The web version fetches its code from our server on every visit. So you have to trust that exactly the published code is sitting there. If you would rather not, use the app for Android or the Linux desktop (installed and verified once, then offline) or the command-line tool from the repo — both run fully offline, with the same calculation core.
You have the rights under Art. 15–21 GDPR (access, rectification, erasure, restriction, data portability, objection) as well as the right to lodge a complaint with a supervisory authority (Art. 77 GDPR). Controller within the meaning of the GDPR: see Impressum.