I have a DHL Packstation near where I live that I use a fair amount to receive packages. Accessing it requires scanning my Post Number barcode (or typing it in manually) followed by entering a PIN that's unique per delivery.
DHL offers a mobile app to manage these PINs, but I felt disinclined to install an app and open myself up to tracking just to manage a few numbers, so instead of using the official app I created my own.
Packstation Companion has two main functions: 1. by swiping down on the home screen, I can unveil the barcode for my Post Number to scan it at the Packstation. (The barcode does not actually encode the plain Post Number, but obfuscates it using some proprietary algorithm. I simply copied the value from my membership card.) And 2. I can add and delete PINs to an internal list. PINs are initially concealed by a small protective layer, which can be swiped to the right to reveal them.
Since this app is simply storing my own data and not interfacing with any DHL APIs, I'm not overly worried that I could be running into problems. Nonetheless, as I am kinda using their trade dress without permission, I am not attempting to publish this app.