Privacy policy Privacy

Contact form

The contact form takes a name (optional), an email address (required), and a message. A Cloudflare Worker receives the submission at /api/contact and hands it to Resend, which delivers it to my inbox as an email.

That message is read only by me. It is not added to any mailing list, not shared with anyone else, and not used for anything other than replying. Resend and my email provider keep the message in their systems for as long as a delivered email normally lives there. The chain will be removed from my inbox once any discussion has concluded.

Cloudflare

The site sits behind Cloudflare, which serves the pages, blocks abusive traffic, and absorbs attacks. To do that, Cloudflare processes the standard request data your browser sends — including your IP address, the URL you requested, your User-Agent string, and similar headers. See Cloudflare's privacy policy for what they retain and for how long.

Cloudflare Turnstile

The contact form uses Cloudflare Turnstile to keep bots out. Turnstile loads a small script from challenges.cloudflare.com and runs a silent check in your browser before the form will submit — there is no puzzle to solve. It shares minimal browser data with Cloudflare to evaluate that check.

No tracking; what the site stores on your device

There is no analytics platform on this site, no advertising script, no fingerprinting, and no cookie set by the site itself. Nothing on the page tries to identify you across visits.

The site does keep a few small preference and progress values in your browser's localStorage so a page can remember your choices between visits: whether you have the US or Metric units toggle selected; whether you have the Dark or Light theme selected; the temperature range you picked on the psychrometric chart; the refrigerant you last used on the refrigerant P-T calculator and the refrigerant loop simulator (they share one memory) and the sensor type you last used on the thermistor calculator; and, on the practice quizzes, your best score and its time, how many times you have attempted each one, and when you last played it.

All of that stays on your device. It is never sent to me or to anyone else, and it is not used to identify you or track you across visits. Clearing your browser's site data for controlsfreak.dev removes it.

Cloudflare may set its own cookies for security and bot protection, independently of anything on this site. Those are covered by their privacy policy linked above.

Your rights

If you are in the EU or the UK, the GDPR (or the UK GDPR) gives you a few rights over data that identifies you. In the case of this site, the data that identifies you is whatever you put into the contact form. You can ask me to send you a copy of what you submitted, correct it, or delete it. To make a request, send a note through the contact form from the same email address you used originally so I can match it up. I will reply as soon as possible. With the current number of emails, that normally means within 24 to 48 hours.

Request data that Cloudflare sees as part of delivering the page is handled under its own policy; if you want to exercise rights against Cloudflare, you would need to contact them directly. (Fonts are served from this site's own domain — no font request leaves it.)

Children

The site is not directed at children under 13 and does not knowingly collect information from them.

Changes to this policy

If something material changes — a new third-party service appears on a page, the contact form starts collecting something new — this page will be updated and the "Last updated" date at the top will move.

Questions

For any privacy-related question, send a note through the contact form.