On an Android phone with Chrome, open the card, go to its NFC chips tab and choose “Program tag”. Hold a blank tag to the back of the phone: the link is written to it and it is linked to the card.

Then tap it once more so the link on it can be checked. You can also lock the tag so nobody can change or wipe it, you included; this can’t be undone.

Tip: iPhone doesn’t let websites write NFC tags. Use an Android phone, or chips from us.