The only thing that we currently save, is the username of the developer, and application names. every 30 minutes, a php scripts executes, and scans the release page of each developer's applications (that we saved).
From this release page we cache the different versions, the contents of the release, date, downloads, ....
When someone visits the website, we call up our cache (a list of all the homebrew applications visible, with their data), and we filter out every application with a CIA (or 3DSX) in it.
We take the download url, and put that inside the get request of an online qr code generator as the url for the images.
so the images you see would be something like
www.qr-code.generator.com/generate?url=github.com/developer/application/releases/versionnumber/filename.cia
However, we thought: what if someone saves this image? people will be using old downloads. So what we did is make this service:
www.homebrewhub.xyz/latest/cia/ShinyMK/JKSMK
(
www.homebrewhub.xyz/atest/cia/<developer>/<application>).
Which will scan our data, and point to the latest download.
Edit: We use the github api