Hey /c/privacy,
Similar to the idea that was proposed a month ago by @to_urcite_ty_kokos@lemmy.world, I built a little web app that allows one to “emulate” EAN13-based loyalty cards. I call it the Loyalty Card Emulator. 🪄
The app allows you to either select one of the built-in card numbers that I have found on the internet. (Only for demonstration purposes, of course!) Or you can just enter a code manually and create the loyalty card from it. The link to a card can be shared (e.g. if you and your SO use the same loyalty card).
At the moment, it is very basic and only has one single design that is supposed to visually mimic one of the biggest loyalty card providers that I know.
Architectural-wise, the app is written in TypeScript, powered by React and Vite. The app does not transmit and/or store your codes anywhere but on your device; it’s a single-page application that runs entirely in your browser, without any server component.
The source code is publicly available here. The hosting is taken care of by Codeberg Pages - cheers for that!
Adding new card designs and/or preset codes can be achieved quite easily, so feel free to fork and contribute!
I can confirm that this is the case at “Albert Heijn” in the Netherlands, where you can “save” a bit of money during checkout if you were to present your loyalty card.