Hadamard LLC

Privacy

Last updated 11 October 2026

This page says what Quantum Tycoon keeps about you, why, where it goes, how long we keep it, and what you can ask us to do with it. We collect as little as the course needs to work. We do not sell your data, and the site has no adverts, analytics or tracking.

Who is responsible

Hadamard LLC runs Quantum Tycoon and is the controller of the data described here. Write to Hadamard LLC, 1309 Coffeen Avenue, Suite 1200, Sheridan, WY 82801, United States, or email info@quantumzeitgeist.com.

Gumroad, Inc. sells the membership as merchant of record. It is a separate controller for everything about the purchase, such as your name, email, address, payment card and tax details. We never see your card number. Gumroad's privacy policy explains what it does with your data.

What we hold, why, and for how long

• Your licence key and purchase status. When you paste your key, our server asks Gumroad whether it belongs to a paid membership. Gumroad's answer includes the purchase date and the email you paid with. We use it to open the course for you and to check about once a day that the membership is still paid. We store the key only inside the sign-in cookie in your browser and keep no list of keys or members. Legal basis: performance of our contract with you.
• Code you run. Run sends the code in the editor to our server, which passes it to a sandbox to run and sends back the result. We do not save the code. Legal basis: performance of our contract.
• Server logs. Google Cloud records each request, with your IP address, browser type, the page asked for and the time. We use these logs to run the service, find faults and stop abuse, and they are deleted after 30 days. We count runs per member, and any free runs per IP address, in memory to apply the run limits, and the counts vanish when the server restarts. Legal basis: our legitimate interest in keeping the service working and secure.
• Anonymous step counts. To see how many visitors move from the home page to the course and on to checkout, the server writes one line per step, such as "opened the course" or "clicked subscribe". The line holds the step name and, for checkout, the plan. It holds no IP address, key, email or cookie, so it cannot be linked to you. The lines are deleted after 30 days with the other logs. Legal basis: our legitimate interest in improving the course.
• Withdrawal and refund requests. If you use the withdrawal form, we keep your name, email, the last 8 characters of your key, the time of the request and what Gumroad says about the purchase. If you email us, we keep the email. We use these to handle the request and keep them for 3 years to show we dealt with it properly. Legal basis: our legal obligations under consumer law, and our legitimate interest in keeping records.
• Emails we send you. Gumroad sends receipts. Through Gumroad, we may email members about renewals, price changes or changes to these terms. These are service messages, and we send no marketing unless you ask for it.

You do not have to give us any of this, but without a licence key the course cannot open.

Cookies and browser storage

The site sets one cookie, called __session. It holds your licence key and an expiry time, signed by our server so it cannot be altered, and it lasts up to 30 days. It keeps you signed in. It is strictly necessary for the service you asked for, so the law does not require a consent banner for it.

The site also saves two items in your browser's local storage. qp-passed lists the sections you have passed, and qp-bench holds the code in the free editor. They stay on your device, and clearing your browser data removes them. There are no other cookies and no third-party cookies. Fonts are served from our own site.

Who else sees it

• Google Cloud and Firebase host the site and the server, mainly in Belgium (europe-west1), and keep the server logs. Google processes the data for us under its Cloud Data Processing Addendum.
• Modal Labs, Inc. in the United States runs the sandbox that executes your code. It receives the code and nothing that identifies you, and processes it for us under its data processing terms.
• Gumroad, Inc. in the United States answers our licence checks and handles payments and refunds, as described above.

We would also share data if the law required it, for example with a court or tax authority.

Data sent outside Europe

Hadamard LLC, Modal and Gumroad are in the United States. When we, or the providers above, move personal data from the EU, the EEA or the UK to the United States, we rely on the EU-US Data Privacy Framework and its UK extension where the recipient is certified. Otherwise we rely on the European Commission's standard contractual clauses and the UK addendum to them. You can ask us for a copy of the safeguards.

Your rights

You can ask us for a copy of the data we hold about you, or to correct it, delete it, restrict how we use it, or send it to you in a portable form. You can object to our use of it on the basis of legitimate interests. Email info@quantumzeitgeist.com. We reply within one month and do not charge. For your purchase record, we will pass the request to Gumroad, or you can contact Gumroad directly.

If you live in the EU or the EEA, you may complain to the data protection authority where you live or work. In the UK, that is the Information Commissioner's Office (ico.org.uk). We would like the chance to fix the problem first, so please write to us too.

If you live in a US state with a privacy law, you have the rights that law gives you, and you can use them the same way. We do not sell or share personal data for advertising.

Children

Memberships are for people aged 18 or over. The course is not aimed at children, and we do not knowingly collect data from anyone under 16. If you think a child has given us data, email us and we will delete it.

Security

The site runs only over HTTPS. The sign-in cookie is marked Secure and HttpOnly, so scripts on the page cannot read it, and it is signed with a secret that only our server holds. Code runs in a sealed sandbox with no network access.

Changes

If we change this page, we will put the new date at the top. If a change matters, for example a new kind of data or a new provider, we will tell members by email before it takes effect.