We have introduced a new range of NFC Tamperproof Stickers that continue to work, but provide an indicator as to whether the item has been opened or not. This is done by a unique antenna system and the NXP NTAG213TT chip. The chip has the same compatibility as the NTAG213 so is compatible with all mobiles on the market enabling the validation of an item using a standard mobile device either Adnroid, Windows or App that has NFC capability built in.
If you do not get us to encode these for you, you can encode them yourself using an Android NFC enabled mobile and the NXP TagWriter tool. You just need to write a URL and choose the Configure Mirror Options and then on the next form select NTAG213TagTamper as your tag type and just accept the defaults initially. Once encoded if the tag is in tack you will get your URL/?tt=00000000 and if it gets broken - next time you tap you will get URL/?tt=FFFFFFFF. A simple way of using this is for the landing page to check the parameter and redirect to a valid product if 00000000 or an invalid product if the value is FFFFFFFF