Privacy Policy

Last updated: 16 September 2026

Car Rental Brain ("we", "the app") helps you find cheap car rentals and, if you choose, alerts you when prices drop. This policy explains what we collect, why, and your choices. We keep it short and honest.

There are no accounts and no passwords. You can use everything here without telling us who you are.

What we collect

  • Search details you enter: pick-up location, dates, driver age, residence country, currency and filters. Used to run your search. Searches are logged (location, dates, filters, time) without any personal identifier, so we can see how the tool is used.
  • Market conditions of each search — how many cars were offered, how many suppliers publish a second-driver fee, typical fees, deposits and price spread. This is about the rental market, not about you, and contains nothing that could identify you. We use it to improve our estimates and to publish what renting actually costs in a given place.
  • Clicks on "Book" and insurance links. When you click through to DiscoverCars or an excess-insurance partner we record that a click happened (which offer, supplier, location and time) so we can measure whether the tool is useful. No personal identifier is attached to a click.
  • Your approximate country, from the country code Cloudflare attaches to the request, used only to pre-select your country of residence in the form. We do not store IP addresses.
  • Your email address — only if you type it in — to (a) email you the results, (b) save a price-drop "watch" and alert you when the price falls, or (c) store the bookings you add under My bookings.
  • We do not collect names, payment details or account passwords. Booking and payment happen on DiscoverCars, not here.

Why we use it

  • To run your car-rental search and show or send you the results.
  • To re-check a saved search and email you only on a meaningful price drop.
  • To show you the bookings you chose to save, keyed by the email you gave.
  • That's it. We do not sell, rent or share your data for advertising.

Who we share it with

  • Resend — our email delivery provider — processes your email address solely to deliver the results or alerts you asked for. Mail is sent from alerts@carrentalbrain.com.
  • Cloudflare — serves the site and forwards mail sent to our addresses. It sees requests in transit as any network provider does.
  • Hetzner — hosts the application server (Nuremberg, Germany). Your data stays in the EU/UK.

  • DiscoverCars — when you click a "Book" link you leave our app for DiscoverCars, whose own privacy policy then applies. We may earn an affiliate commission on completed bookings (see our Affiliate Disclosure) — at no extra cost to you.

  • Cloudflare Web Analytics — counts page views and measures how quickly pages load. It sets no cookies, does not fingerprint your device, and cannot follow you to any other website. It records the page address, referrer, country, and browser and device type. There is no identifier that links one visit to another, so nothing here can be traced back to you.

  • Microsoft Clarity — shows us anonymised heatmaps and replays of how pages are used, so we can find the parts of this site that confuse people. We run it in Microsoft's strict masking mode, which means all text is masked before it leaves your browser: a replay shows where a cursor moved, what was clicked and how far the page was scrolled, not what anything said or what anyone typed. We have also switched Clarity's cookies off, so it sets none — including Microsoft's advertising cookies, which it would otherwise set. It is not loaded at all on My bookings, on watch pages, or on unsubscribe pages, because those are the only pages where your email address is on screen.

We do not use Google Analytics, advertising pixels, or any tracker that follows you across websites. The two analytics tools we use are named above, and both are the cookieless kind.

Storage & retention

  • Watches (your email plus the search you asked us to track) are stored so we can re-check them. They are deleted when you unsubscribe — there is a one-click link in every alert email.
  • Saved bookings (what you entered under My bookings, keyed by your email) are kept until you remove them; there is a Remove button on each one.
  • Anonymous search and click logs are kept as an operating record of how the tool is used. They contain no personal identifier and cannot be traced back to you.
  • We keep data only as long as needed for the above.

Cookies

The app sets no marketing or tracking cookies at all — including both our analytics tools, which are deliberately configured to set none. Microsoft Clarity would by default set advertising cookies; we have turned that off, and the trade we accepted for it is that we cannot follow one person from page to page. It may remember your last search and your light/dark choice in your own browser's local storage — that never leaves your device and we never see it. When you click through to DiscoverCars or an insurance partner, they set their own affiliate and analytics cookies under their policies.

Your rights

You can ask us to access, correct or delete anything we hold that is linked to your email, and we will action it. Where the UK GDPR applies, our basis for processing your email address is your consent, which you can withdraw at any time by unsubscribing or asking us. You also have the right to complain to the Information Commissioner's Office (ico.org.uk).

  • Stop price-drop emails: click unsubscribe in any alert, or email us.
  • Delete your bookings: remove them on the My bookings page, or email us.

Contact

Questions or requests: hello@carrentalbrain.com