Privacy Policy
This page explains which personal data hotmilk.ch processes, why, and what rights you have. It follows the Swiss Federal Act on Data Protection (FADP) and, where it applies, the EU General Data Protection Regulation (GDPR).
The hotmilk app for iOS and Android has a privacy policy of its own.
Last updated: October 2026
Controller and contact
Stephan Mathys
Switzerland
dive@hotmilk.ch
hotmilk.ch, the website and the app, is a private project. Write to the address above for any question about your data.
In short
- You can use the calculators without an account. hotmilk.ch then only keeps the server logs described below.
- hotmilk.ch uses no analytics, no tracking and no social media plugins.
- hotmilk.ch does not sell your data or use it for advertising.
Account and login
The website and the app use the same account. If you register, hotmilk.ch stores:
- your first and last name and your email address,
- your password, only as a salted hash,
- your dive organisation and level, if you enter them,
- what you save in your settings: tanks with their inspection dates, planner profiles and filling stations with their prices.
An administrator reviews every registration before the account becomes active. The data is used to run your account and the features you use with it (Art. 6(1)(b) GDPR). It is kept as long as your account exists. If you ask for your account to be deleted, it is deleted together with everything you saved in it.
Cookies
When you log in, the website sets a session cookie. It keeps you logged in and protects the forms against cross-site request forgery. It is sent only over HTTPS and ends after 12 hours without activity or when you log out. The website cannot work without it, so it needs no consent. The website sets no other cookies.
Mails
When you register, your details go by mail to the administrator, who approves or rejects the registration. You then get a mail with a link to set your password, or a mail with the reason for the rejection. You also get a mail when you reset your password. The mails go out through the mail service of Google Workspace (Google Ireland Limited and Google LLC, USA), which processes your email address and the content of the mail on behalf of hotmilk.ch.
Voluntary contributions through Stripe
Logged-in users can make a voluntary contribution. The payment takes place on a page of Stripe (Stripe Payments Europe, Ltd., Ireland). Stripe processes your payment details under its own privacy policy; hotmilk.ch never sees your card details.
hotmilk.ch stores the amount, the currency, the time, the status of the payment and the reference of the Stripe session, linked to your account. This data is used to process the contribution (Art. 6(1)(b) GDPR) and is kept as long as your account exists, or longer where the law requires it.
Hosting and server logs
The website and the interface the app talks to run on Amazon Lightsail of Amazon Web Services in Frankfurt, Germany. For every request the server logs your IP address, the date and time, the requested address, the response status, the referring page and the browser or app you use. The logs serve to operate the website and the app, to find errors and to defend against attacks (legitimate interest, Art. 6(1)(f) GDPR). They are deleted after 14 days at the latest.
Disclosure abroad
The data is stored in Germany, which offers an adequate level of data protection. Google, Stripe and Amazon Web Services are groups with headquarters in the USA, so data may be accessed from there. Where this is the case, the transfer is based on the EU-U.S. and Swiss-U.S. Data Privacy Framework or on the standard contractual clauses of the European Commission.
Your rights
You have the right to:
- know which data about you is stored,
- have wrong data corrected,
- have your data deleted,
- restrict or object to its processing,
- receive your data in a common electronic format.
Write to the address above. You can also lodge a complaint with the Federal Data Protection and Information Commissioner (FDPIC) or, in the EU, with the data protection authority of your country.
Changes
This policy changes when the website starts processing data in a new way. The date at the top shows the last change.