Privacy Policy
Q.E.D
Last updated: 21 September 2026
This page explains how personal information and data are handled in the iPhone app Q.E.D (the App), and describes the analytics used on this website, which introduces the App.
1. Information we collect
The App collects no personal information of any kind.
It does not obtain your name, email address, telephone number, location, contacts, or photos. It obtains no identifiers for analytics or advertising.
The App is accordingly declared as Data Not Collected in its App Store privacy details.
2. What is stored on your device
The entries you bookmark, and the number of times you have left a tip, are stored only on your device, using the standard iOS storage mechanism (UserDefaults).
None of this is transmitted to the developer or to any third party. Deleting the App removes it from your device.
3. In-app purchases (tips)
The App offers an optional tip, as a consumable in-app purchase through Apple's StoreKit, for anyone who wishes to support the work.
Paying unlocks no functionality of any kind. All of the App's content is available for free.
Payment details such as card numbers are never obtained or stored by the App or its developer; they are handled by Apple (the App Store). The App communicates with Apple only to confirm a purchase.
4. Network connections
All content is bundled with the App, and no connection is required to read it.
A connection occurs only in the following cases: when completing a tip purchase (communication with Apple), when opening a location from Places (which opens Apple Maps), and when opening the App Store review screen. In none of these cases does the App transmit data of its own.
5. Accounts and advertising
No account or sign-in is required to use the App.
No advertising is shown within the App.
6. Analytics on this website
This website is hosted on Firebase Hosting and uses Google's Firebase Analytics (Google Analytics for Firebase) to understand how the site is used.
This may collect information such as the pages viewed, the referring source, an approximate region, and the type of device and browser. This concerns visits to this website only, and is unrelated to your use of the App.
For details of Firebase Analytics, please refer to Google's privacy policy.
7. Third-party services
The App and this website make use of services provided by Apple (App Store, StoreKit, Maps) and Google (Firebase). Data handling within each of those services is governed by the respective provider's privacy policy.
8. Children's privacy
The App is rated 4+ and contains nothing requiring an age restriction.
Because the App collects no personal information from any user, it collects none from children either.
9. Changes to this policy
This policy may be revised without notice to reflect changes in law or in the App or this website. Any revision takes effect when it is posted on this page.