ive just heard of an incident where students redirected their books codes to p**n. can i make sure that doesnt happen? also, im using google to generate them, is there a foss alternative as im scared of tracking. lastly, can i make the qr code redirect to a specific page of a pdf as i want people to be able to scan them and immediately land on a specific part
This is kind of confusing, or at least leaves a lot of detail out 😆 Did the domain lapse? Did their short-URL account get hacked? In any case, your QR code will just be encoding a URL. Ultimately, any URL can be redirected by someone out there; so it's just a matter of trusting that whoever has that access won't act maliciously, and that malicious actors can't gain access.
There absolutely are, just search and you should find plenty. Again, though, the QR code is just encoding a URL. Does Google use their own short-URL service for their generated QR codes? Just scan the QR code and look at the URL it encodes. If it's only the URL you want - not some Google short-URL that then redirects to the URL you entered - then there can't be any tracking done on it by Google.
Covered by another commenter already, but for completeness: yes, you just add
#page={n)at the end of the URL, e.g. https://dagrs.berkeley.edu/sites/default/files/2020-01/sample.pdf#page=5