Privacy Policy

The German version is authoritative. Deutsch

This privacy policy applies to the website nixstein.ai-design-thinking.de and the NixStein app for Android. It describes which personal data we process, for what purpose and on what legal basis (Art. 13 GDPR).

1. Controller

Victor von Rautenberg
Pfarrer-Theile-Str. 97
13591 Berlin
Germany

Email: admin@ai-design-thinking.de

We have not appointed a data protection officer; there is no obligation to do so.

2. Hosting

The website and the app server run on a server at Hostinger (data centre in Germany). The contractual partner is Hostinger International Ltd., 61 Lordou Vironos str., 6023 Larnaka, Cyprus. Hostinger processes the data exclusively on our behalf (processing on behalf of the controller under Art. 28 GDPR).

3. Visiting the website

Each time a page is accessed, the server processes technically necessary data:

• IP address
• date and time
• requested address (URL) and status code
• browser identifier (user agent)

This data is kept in an access log, which is deleted after 48 hours; access credentials are redacted in it. The purpose is secure and stable operation, in particular the defence against attacks. The legal basis is Art. 6(1)(f) GDPR; our legitimate interest is precisely this secure operation.

To protect against misuse, an IP address is temporarily blocked in the event of an unusually high number of requests or repeated failed attempts, for no more than 2 hours.

The website does not set any advertising or analytics cookies and stores nothing in your browser (not even Local Storage). The only exception: if you select “Sign in with Google”, our server sets a short-lived, technically necessary cookie for the duration of the sign-in process (valid for 10 minutes, only for the path /api/v1/auth/google) in order to securely associate the sign-in with your browser. No consent is required for this (§ 25 Abs. 2 Nr. 2 TDDDG, a provision of the German Telecommunications Digital Services Data Protection Act). There are no analytics or statistics services, no advertising, no social media plug-ins and no third-party content; fonts, images and scripts come from our own server.

4. Registration (website and app)

For an account, we process:

• the name you enter as keeper
• your email address
• your date of birth
• the language you have chosen
• the time of your consent to this privacy policy

We send you an email with a confirmation link (double opt-in). The account is confirmed only once you click it; we delete unconfirmed accounts after 7 days. The date of birth serves only for the age check: NixStein is for ages 16 and over (Art. 8 GDPR). For signing in on another device, we send you a sign-in code by email on request.

The legal basis is Art. 6(1)(b) GDPR (provision of the account and the app). Without this information we cannot create an account.

As proof of your consent and of the confirmation (double opt-in), we store the IP address and the time of registration and of confirmation until you delete your account. The legal basis is Art. 6(1)(c) GDPR in conjunction with Art. 7(1) GDPR (obligation to demonstrate consent) or Art. 6(1)(f) GDPR (proof and defence against misuse).

For every new registration, the operator receives an internal notification by email containing the registration data (name, email address, date of birth, language, source – website or app –, time and IP address). It serves support and the defence against misuse; the legal basis is Art. 6(1)(f) GDPR. It is delivered via Hostinger's mail server to the operator's mailbox.

Sign-in with Google: instead of using the form, you can sign in with your Google account. You are only redirected to Google once you click “Sign in with Google”; no connection to Google is established beforehand. The provider is Google Ireland Limited, Gordon House, Barrow Street, Dublin 4, Ireland. From Google we receive only your Google identifier, your e-mail address, your first name and an indication of whether the e-mail address has been verified. If an account with this e-mail address already exists, we link it to it.

The legal basis is Art. 6(1)(b) GDPR. Google’s privacy policy applies to the processing by Google: https://policies.google.com/privacy

5. The app

• Stones and chain of keepers: For each stone, we store to whom it belongs and since when, as well as the eyes it wears. Later keepers of a stone can see the names of the previous keepers. If you delete your account, only “—” appears in your place.
• Diary notes and conversations with the stone remain on your device and are not transmitted to us.
• Location, only with your consent (Art. 6(1)(a) GDPR): The app asks once and uses only the approximate location, never GPS-precise and never in the background. Already on the device it is rounded to about 2 km and is transmitted only while the app is open. We store the last position per stone (deleted after 30 days without a new report) and a travel route accurate to about 20 km with at most 500 points per stone, which only the current holder sees. Others see in the Stoneradar only a rough distance band (under 5, 10 or 25 km) and the number of stones in a city, no names and no positions. You can withdraw your consent at any time in the app’s Settings (“Share location”).
• City: From the first location report, our server determines your city once, offline and without an external service. The rounded home location and the city are stored. Place names: GeoNames (https://www.geonames.org), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
• Step counter (walkies): Your device counts the steps using activity recognition. Steps and distance remain on the device.
• Swapping: The devices find each other directly via Bluetooth, Wi-Fi or NFC (Google Nearby Connections); the swap is completed via our server. No location is stored in the process.
• The app schedules notifications on the device. There is no push service and no Firebase.
• Updates: At start-up, the app asks our server for a new version. In doing so, your IP address is recorded in the access log (see section 3).

The legal basis for the app’s functions is Art. 6(1)(b) GDPR, and for location your consent.

6. Payments via Stripe and withdrawal

You pay for purchases in the app (unlocking, eyes, additional stones, gifts) on Stripe’s payment page. Stripe Payments Europe Ltd., 1 Grand Canal Street Lower, Dublin 2, Ireland, processes your payment data (e.g. card or PayPal data) as an independent controller. Information on this: https://stripe.com/de/privacy

We transmit to Stripe the product, price, order number and your email address (for the receipt); from Stripe we receive the payment status, amount and identifiers of the transaction. We do not receive card data. The legal basis is Art. 6(1)(b) GDPR. We retain accounting records for 10 years due to statutory obligations (§ 147 AO [German Fiscal Code], § 257 HGB [German Commercial Code]; Art. 6(1)(c) GDPR), even beyond deletion of the account.

Withdrawal: If you use the withdrawal function (“Withdraw from contract” button), we process your name, your email address, where applicable the order number and the time, in order to handle and document the withdrawal. The legal basis is Art. 6(1)(c) GDPR; we retain this information for 10 years (§ 147 AO, § 257 HGB).

7. Giving a stone as a gift

If you give a stone as a gift, we process the recipient’s email address and, if provided, their name and your message, solely in order to deliver the gift. The recipient receives exactly one email with a code. As soon as the gift has been redeemed, and at the latest after it expires (1 year), we delete the address, name and message. To defend against misuse, a hash value of the address remains; gifts that have not been redeemed are deleted entirely 30 days after expiry, while redeemed gifts remain without an address for as long as the recipient’s account exists.

The legal basis is Art. 6(1)(b) GDPR (your purchase) and, for notifying the recipient, Art. 6(1)(f) GDPR (legitimate interest in delivering the gift).

8. Sending emails

Emails (confirmation, sign-in code, gift, purchase confirmation, acknowledgement of receipt of a withdrawal, internal notification of new registrations) are sent via the mail server of Hostinger (smtp.hostinger.com), likewise on our behalf under Art. 28 GDPR.

9. Retention period

10. Disclosure, third countries, profiling

We do not share your data with third parties, except with Hostinger as a processor, with Stripe for purchases and, if you use “Sign in with Google”, with Google. We ourselves do not transfer any data to countries outside the EU. Stripe and Google may also transfer data to the USA; Stripe, Inc. and Google LLC are certified under the EU-US Data Privacy Framework. There is no automated decision-making and no profiling (Art. 22 GDPR).

11. Your rights

You have the right to:

• access (Art. 15 GDPR)
• rectification (Art. 16 GDPR)
• erasure (Art. 17 GDPR)
• restriction of processing (Art. 18 GDPR)
• data portability (Art. 20 GDPR)
• object to processing based on Art. 6(1)(f) GDPR (Art. 21 GDPR)

You can withdraw consent at any time with effect for the future (Art. 7(3) GDPR), for example by switching off “Share location” in the app. You delete your account in the app under Settings → “Delete account”; this deletes the account, stones and positions. For everything else, an email to admin@ai-design-thinking.de is sufficient.

You can also lodge a complaint with a data protection supervisory authority. The authority responsible for us is the Berlin Commissioner for Data Protection and Freedom of Information (Berliner Beauftragte für Datenschutz und Informationsfreiheit), Alt-Moabit 59–61, 10555 Berlin, https://www.datenschutz-berlin.de

Last updated: 15.10.2026