Privacy Policy

August 25, 2026

[Controller: legal name, postal address], contact: [privacy@…] (the "we").

This policy covers the website 7cows.io and the calculators on it. It is written to satisfy the EU/EEA General Data Protection Regulation (GDPR) and the Swiss Federal Act on Data Protection (revFADP), which impose substantially the same obligations on us.

The short version

We run this site with as little data as we can get away with:

• No cookies. We set none, for any purpose.
• No third-party trackers, no advertising, no profiling, no sale of data.
• No content delivery networks. Every script, stylesheet and font is served from our own servers, so your browser never contacts a third party while loading a page.
• No account needed. You can use every calculator without telling us who you are.
• Analytics are self-hosted on our own machines, without cookies. Nothing is shared with an analytics company, because there isn't one.

What we process

Server logs

Our web server records each request: the shortened IP address (the last block is discarded before writing, so 203.0.113.42 is stored as 203.0.113.0), the time, the page requested, the HTTP status, the referring page and the browser's user-agent string.

• Purpose: keeping the site running, diagnosing errors, defending against abuse and attacks.
• Legal basis: our legitimate interest in a functioning and secure service, GDPR Art. 6(1)(f).
• Retention: [14] days, then deleted automatically.

Usage statistics

We run two self-hosted analytics tools on our own servers — Umami (data.7cows.io) and Shynet (stats.7cows.io). Neither sets a cookie or stores anything on your device. They record the page visited, the referring page, and coarse browser, operating-system and screen-size information. To tell one visit from another they derive a short-lived hash from your IP address and user agent; the address itself is not kept.

• Purpose: seeing which pages and calculators are used, so we can improve them.
• Legal basis: legitimate interest, GDPR Art. 6(1)(f). Because no information is stored on or read from your device, no consent banner is required.
• Retention: [12] months in aggregate form.
• Recipients: none. The data stays on our servers.

Your calculations

Calculator inputs are processed to compute a result and are not stored in any database. When you create a permalink, the figures are encoded into the link itself — nothing is written on our side. A permalink therefore contains whatever you typed: treat sharing one exactly as you would treat sharing the numbers.

Newsletter

If — and only if — you subscribe, we store your e-mail address, the date of your subscription and the confirmation of it. Subscription is double opt-in: you receive one e-mail asking you to confirm, and nothing is sent until you do.

• Purpose: sending the newsletter you asked for.
• Legal basis: your consent, GDPR Art. 6(1)(a), withdrawable at any time with no explanation.
• How to leave: the unsubscribe link at the foot of every issue. From the same page you can export or delete the data we hold about your subscription yourself.
• Processor: the mailing software (Listmonk) runs on our own server; delivery goes through [e-mail delivery provider].

Stored in your browser

The site remembers your theme (light or dark) and, briefly, your entered values while you switch languages. Both live in your browser's own storage, never reach us, and are there because you asked for that behaviour. Clearing your browser data removes them.

Where the data is

Our servers are operated by [hosting provider, location]. We do not transfer personal data outside the EU/EEA or Switzerland.

Your rights

You have the right to access the data we hold about you, to have it corrected or deleted, to have its processing restricted, to object to processing based on legitimate interest, and to receive it in a portable form. Write to [privacy@…] and we will answer within one month.

Given how little we keep, be aware that we usually cannot identify you from it: shortened IP addresses and cookieless statistics cannot be traced back to a person, so for those we may be unable to act on a request (GDPR Art. 11) — which is the point of collecting them that way.

You may also complain to a supervisory authority — in Switzerland the Federal Data Protection and Information Commissioner (FDPIC), in the EU/EEA the authority of your country of residence.

Changes

We update this policy when what we do changes. The date above is the current version's date.