I'm not a coder - which will become obvious! I need to be 100% sure on this before I explain to my boss.
Is it at all possible for a website to dig out some kind of unique identifier from a phone? He is proposing that an NFC tag will send someone to a website where there will be an offer, and he needs it to be a one time offer, thus trying to find an identifier to lock them out of repeatedly claiming.
I've suggested using data capture and SMS but he is set on it being as simple for the user as possible, eg scan - claim - done.
As far as I know this is not possible... :S
I really appreciate any comments.
Depends on what form of UID you want.
If you're talking about telephony ID, MAC address, serial number, and/or Android ID then no.
Even native apps would require a non-standard permission from the user to access that kind of information (READ_PHONE_STATE), let alone a website.
That said, there are many ways to identify users of a website. You might want to look at user agents or cookies which can and has been used to achieve similar goals. In this regard, Android devices bear no difference to your typical web browser and thus are identifiable.