Privacy Policy
1.Privacy at a Glance
The following notes provide a simple overview of what happens to your personal data when you visit this website.
Who is responsible for data collection on this website?
Data processing on this website is carried out by the website operator. You can find their contact details in the legal notice of this website.
Pursuant to Art. 13(2)(e) GDPR, we would like to point out that providing data in our contact forms is voluntary. Without providing certain mandatory fields (e.g. email address), the respective request cannot be processed.
2.No Data Storage for Calculations
Important: All calculations you perform on this website take place exclusively in your browser (client-side). Calculator inputs are only processed locally and are not transmitted to our servers.
- Not transmitted to our servers
- Not stored
- Not shared with third parties
- Deleted when the browser is closed
Optional Permalink (URL Fragment)
Some calculators offer the option of saving your inputs as a permalink. The inputs are encoded exclusively in the URL fragment (the part after the # character). For technical reasons, URL fragments are never transmitted to our servers — they remain exclusively in your browser. Calculators with health-related inputs (e.g. pregnancy, date of birth, body measurements) never write any data to the URL.
3.Hosting and Analytics
Hosting
This website is hosted on a server in Germany (Hetzner). Server log files are automatically deleted after 7 days.
- • Browser type and version
- • Operating system used
- • Referrer URL, hostname, IP address
- • Time of the server request
Umami Analytics (cookie-free, self-hosted)
We use Umami Analytics, a privacy-friendly and GDPR-compliant analytics solution, operated at analytics.headon.pro.
- • Sets no cookies and creates no persistent identifiers
- • Stores no personal data
- • Does not collect IP addresses
- • No cross-device or cross-session recognition
- • Self-hosted on our own servers in Germany (Hetzner)
- • Raw statistics data is deleted after 12 months at the latest
No consent required.
Global Privacy Control (GPC): If your browser sends the GPC signal (privacy opt-out), the analytics script is not loaded. We evaluate and respect this signal.
Legal basis: Art. 6(1)(f) GDPR (legitimate interest in anonymous traffic measurement to improve our offering).
Local Storage (localStorage)
The following entries are stored in your browser's local storage (localStorage). This data never leaves your device and is not transmitted to us or third parties.
| Key | Purpose | Lifetime | Deletion method |
|---|---|---|---|
rechnerzentrale:brutto-netto:v1 | Stores the values last entered in the gross-net calculator (incl. tax class, federal state, church membership). Church membership is considered a special category of data (Art. 9 GDPR) — however, it never leaves the device. | Until manually deleted | "Reset" button in the gross-net calculator or browser settings |
rechnerzentrale:<rechner>:v1 | The same storage scheme as the gross-net calculator (values last entered per calculator) is currently also used by the following calculators: active pension, EV subsidy, mother's pension, early retirement pension, pension tax, mini-job, retirement savings plan, as well as the notes calculator (there as calculation history/tape under the prefix tape:). None of these calculators collect special categories of data under Art. 9 GDPR. | Until manually deleted | Browser settings or button below |
rechnerzentrale:app:recents:v1 / :favorites:v1 | Remembers recently used calculators and starred favorites (calculator identifiers only, no input values) — for the personal quick-access sections on the homepage and the app home screen. | Until manually deleted | Browser settings or button below |
pwa-install-dismissed | Remembers whether the PWA install prompt was dismissed. | 7 days | Automatically after expiry or via browser settings |
Banner-Dismiss-Flags | Stores whether notice banners (e.g. calculator request) have been dismissed. | Varies per banner | Browser settings or button below |
sessionStorage is used exclusively for technical deduplication keys (e.g. protection against double-clicks when submitting forms). These entries begin with the prefix rz_ and are automatically deleted when the browser tab is closed.
Legal basis: Sec. 25(2) No. 2 TDDDG (German Telecommunications Digital Services Data Protection Act; storage on the end device is technically necessary or expressly desired by the user to provide the convenience function). Art. 6(1)(f) GDPR additionally applies to the processing of data contained in localStorage (legitimate interest in restoring the last used state).
Anonymized Usage Statistics
To improve our offering, we collect anonymized usage statistics. This data is not personal data and cannot be attributed to any individual.
What we collect (anonymized):
- • Which calculators are used (e.g. gross-net)
- • Categorized input values (e.g. salary range "€3,000-4,000", never exact amounts)
- • Tax class distribution and federal state selection
- • General usage patterns (e.g. dwell time in second-based ranges)
What we do NOT collect:
- • No exact salaries or amounts
- • No personal data
- • No IP addresses or device IDs
- • No persistent identifiers; no cross-session linking
These anonymized statistics help us improve our calculators and develop relevant new features. The legal basis is Art. 6(1)(f) GDPR (legitimate interest).
4.Affiliate Partners
Recommendation links (affiliate links) from three partner networks are embedded on this website. All affiliate links are marked with the notice "Ad" as well as the attribute rel="sponsored noreferrer". Partner logos are loaded from our own server — your browser makes no contact with partner servers before a click.
Data flow: Data only flows to our partners once you actively click a link marked "Ad". This transmits your IP address and user agent to the respective partner, which is technically unavoidable. The referrer is suppressed by rel="noreferrer". Calculator results and your inputs are never transmitted to partners. Advertising texts are adapted exclusively in your browser based on your results. We additionally count clicks on affiliate links anonymously in our own statistics (Umami, see above) — without IP address and without a persistent identifier; the GPC signal is respected here as well.
Legal basis (all partners): Art. 6(1)(f) GDPR (legitimate interest in financing the free offering through commissions). Our partners only set cookies on their own pages after the redirect has taken place.
financeAds GmbH (financeads.net)
Purpose: brokering offers from the financial sector. After clicking a financeAds link, you are redirected to the respective advertising partner's landing page. financeAds only sets cookies on its own pages for success measurement and transaction documentation.
Privacy policy: financeads.net/datenschutz
Awin AG (CHECK24, Aroundhome, FastBill, smartsteuer)
Awin AG, Eichhornstraße 3, 10785 Berlin. Purpose: brokering contextually relevant products via the Awin network. Currently placed advertisers: CHECK24 (electricity, gas, travel and rental car comparison), Aroundhome (renovation offers: photovoltaics, heating, facade insulation), FastBill (invoicing and accounting software), and smartsteuer (online tax return, a temporary replacement for a currently unavailable financeAds category). After clicking an Awin link, you are redirected to the respective advertiser's landing page. Awin or the advertiser only sets cookies on its own page.
Privacy policy: awin.com/de/datenschutz
Tarifcheck.de GmbH
Tarifcheck.de GmbH, Zollstraße 11b, 21465 Wentorf. Purpose: brokering insurance offers via Tarifcheck — currently placed on car insurance (mobility/car calculators) as well as occupational disability insurance (salary calculator cluster). After clicking a Tarifcheck link, you are redirected to the comparison platform. Tarifcheck only sets cookies on its own pages.
Privacy policy: tarifcheck.de/info/datenschutz
Contextual Adaptation of Advertising Content
The advertising texts shown are automatically adapted based on your calculator results (e.g. "At €X net..."). This adaptation takes place exclusively in your browser. Calculator results are never transmitted to us or third parties.
5.Affiliate Link Redirection
Clicks on affiliate recommendations are redirected to the respective provider's landing page via an endpoint on our domain (/api/r/<token>). This allows us to use clean, descriptive links instead of the original tracking URLs.
The following is processed when you click such a link:
- • Your IP address (technically unavoidable for HTTP requests to our server)
- • User agent (browser/operating system)
- • Time of the click and the selected affiliate slot
This data is recorded exclusively anonymized in Umami as a click event and is not permanently linked to your person. After the redirect, the respective partner's privacy policy applies.
Legal basis: Art. 6(1)(f) GDPR (legitimate interest in a clean link structure and success measurement).
6.Document Scan (Local Text Recognition)
Some calculators offer an optional document scan feature that lets you import an image or file to automatically fill in input fields. Text recognition (OCR) takes place exclusively locally in your browser using the Tesseract.js library (WebAssembly). All related files are loaded from our servers — no data is transmitted to external OCR services.
- • The uploaded image never leaves your device
- • The recognized text is neither stored nor transmitted
- • No storage of the image in the browser (neither localStorage nor sessionStorage)
The only information transmitted is an anonymous usage event via Umami (which calculator, which document profile, success or failure of recognition) — without content or personal data.
Legal basis: Art. 6(1)(f) GDPR (legitimate interest in improving our offering through anonymous usage statistics).
7.Contact Forms
B2B Contact Form
If you contact us via the B2B contact form, the data you provide (company, email, if applicable phone and website) is sent to our mailbox by email. No storage in a database takes place — the data remains in the email correspondence.
Retention period: The data is retained until the request has been finally processed, and deleted after 6 months at the latest, unless a business relationship is established. If a business relationship is established, the statutory retention periods apply (Sec. 147 of the German Fiscal Code (AO), Sec. 257 of the German Commercial Code (HGB): up to 10 years).
Legal basis: Art. 6(1)(b) GDPR (pre-contractual measures).
Calculator Request Form
Using the "Request a calculator" button, you can suggest calculators you are missing. The following is processed: the request text, optionally your email address for follow-up questions, as well as a pseudonymized hash value of your IP address (see the Data Security section). The entries are stored in our database and simultaneously sent to us by email.
Providing an email address is voluntary. In this case, you are separately asked for your consent (checkbox); the time of consent is logged.
Legal basis: Art. 6(1)(f) GDPR (legitimate interest in product improvement); if an email address is provided, additionally Art. 6(1)(a) GDPR (consent).
Retention period: Request texts without an email address are pseudonymized after evaluation; with an email address, the address is automatically deleted (anonymized) after 12 months at the latest. Right of withdrawal: consent given may be withdrawn at any time with effect for the future (by email to [email protected]). The lawfulness of processing carried out until the withdrawal remains unaffected (Art. 7(3) GDPR).
8.Data Processors and Recipients Used
We use the following service providers, who process data on our behalf pursuant to Art. 28 GDPR:
Hetzner Online GmbH (Germany)
Hosting of the website and server infrastructure. Location: Germany. Data processing agreement (DPA) concluded. No transfer to third countries.
Supabase Inc. (EU – Frankfurt)
Database for incoming calculator requests. Processing exclusively in the eu-central-1 (Frankfurt am Main) region. Data processing agreement concluded pursuant to Art. 28 GDPR. No data transfer to third countries takes place during database operation.
Resend (Zeno Mail Inc., USA)
Sending of transactional emails (notifications about incoming B2B inquiries and calculator requests to our mailbox). Data processed: sender's email address, content of the inquiry. Provider based in the USA; the transfer is based on Standard Contractual Clauses (SCC) pursuant to Art. 46 GDPR.
Umami (Self-Hosted, Germany)
Anonymous traffic measurement. Operated by us on our own Hetzner servers in Germany — no external data processor, no transfer to third countries.
Affiliate Partners (Recipients, no DPA)
When you click affiliate links, your technical access data (IP address, user agent) is transmitted to the respective partner. The partners are independent controllers within the meaning of the GDPR:
- • financeAds GmbH — financeads.net
- • Awin AG — Eichhornstraße 3, 10785 Berlin (network; current advertisers: CHECK24, Aroundhome, FastBill, smartsteuer)
- • Tarifcheck.de GmbH — Zollstraße 11b, 21465 Wentorf
9.Your Rights
You have the right at any time to:
- 1Request information about your data (Art. 15 GDPR)
- 2Rectification of incorrect data (Art. 16 GDPR)
- 3Erasure of your data (Art. 17 GDPR)
- 4Restriction of processing (Art. 18 GDPR)
- 5Object to processing (Art. 21 GDPR)
- 6Data portability (Art. 20 GDPR)
Withdrawal of Consent (Art. 7(3) GDPR)
Consent given (e.g. to store your email address in the calculator request form) can be withdrawn at any time with effect for the future. The lawfulness of processing carried out until the withdrawal remains unaffected. To withdraw, please email [email protected].
10.Right to Lodge a Complaint with the Supervisory Authority
You have the right to lodge a complaint with a data protection supervisory authority regarding our processing of your personal data. The supervisory authority responsible for us is:
The State Commissioner for Data Protection and Freedom of Information of Baden-Württemberg
Lautenschlagerstraße 20
70173 Stuttgart
Phone: 0711 615541-0
Email: [email protected]
11.Data Security
For security reasons, this site uses SSL or TLS encryption. You can recognize an encrypted connection by the lock symbol in your browser's address bar and the "https://" in the address line.
IP pseudonymization for rate limiting: To protect our form endpoints (B2B lead, calculator request) from abuse, we calculate a SHA-256 hash value of your IP address using a secret server pepper. The original IP address is not stored; only the truncated hash remains, which allows detection of repeated submissions within 24 hours without making it possible to re-identify you.
12.Currency and Amendment of this Privacy Policy
Due to the further development of our website or changes in statutory or regulatory requirements, it may become necessary to amend this privacy policy.
13.App Version (Android App & Installable Web App)
Rechner Zentrale is also available as an installable app — as a Progressive Web App (PWA) directly through your browser, and as an Android app in the Google Play Store.
Android App as a Trusted Web Activity (TWA)
The Android app is technically a Trusted Web Activity (TWA): it loads the exact same website, rechnerzentrale.com, in a Chrome runtime on your device — without its own app interface and without separate program code. The same data processing takes place as when visiting the website in a browser (see sections 1–12 of this policy). The app collects no additional data and requires no additional permissions (e.g. camera, location, contacts) beyond those of the browser.
Obtaining the App via Google Play
Obtaining and installing the app via the Google Play Store is additionally subject to data processing by Google Ireland Limited, Gordon House, Barrow Street, Dublin 4, Ireland ("Google"). This includes, for example, account information as well as installation and usage statistics of the Play Store itself. We have no influence over this data processing.
Google's privacy policy: policies.google.com/privacy
Local Data in the App
Favorites, recently used calculators, and calculator inputs are stored — just as in the browser — exclusively in the app's on-device storage (localStorage). This data is not transmitted to us. You can remove it at any time using the "Delete all locally stored data" button on this page, or by uninstalling the app.
Data Controller
Onur Cirakoglu
HEADON Kreativagentur
Am Vogelsberg 8
97922 Lauda-Königshofen