How to write a link to an NFC card (and not lock it by accident)
Our cards ship blank and unlocked. Writing the destination takes about two minutes on a phone — the part worth planning is what happens afterwards.
Before you write anything
Decide the destination first, and test it in a browser. For review cards the link comes from your Google Business Profile — use the "ask for reviews" link it gives you rather than hand-building a URL. For social or contact cards, a link-in-bio page is usually better than a raw profile URL, because you can change what sits behind it later without re-writing every card.
Keep it short. Chip memory is the constraint (see the NTAG comparison), and short links also survive being read aloud or typed by hand.
Writing the tag
Any phone with NFC can do this; no special hardware is needed for NTAG cards.
- Install a free writer app — NFC Tools is the one we use and recommend.
- Open the "Write" tab and add a record of type URL (or "Website"), then paste your link.
- Hold the phone flat against the card and wait for the confirmation tone.
- Read the card back with the same app to confirm the record is there and complete.
- Test with a second phone, because a phone that just wrote the tag can cache the result.
Locking: the one irreversible step
NTAG chips can be set to read-only. Do it only after the link is final and tested on at least two devices — locking cannot be undone. If there is any chance the destination will change, leave the card unlocked and treat the link as a redirect you control, so you can point it somewhere else later.
Unlocked cards can be overwritten by anyone who taps them with a writer app. For giveaways and public-facing cards, that is usually an acceptable trade; for access control it is not, which is why those projects lock the tag and manage it with a proper system.
What affects whether it actually taps
The antenna in a CR80 card is a loop around the edge of the card, so the middle of the card is the dead zone. Tap the phone near the edge, not the centre. Thick metal phone cases, magnetic mounts and cards stacked on top of each other all shorten the read range. iPhones read tags in the background from the lock screen; Android needs NFC switched on and the screen unlocked.
FAQ
Can a customer overwrite my link?
If the card is unlocked, yes — anyone with a writer app can. Lock the tag if that matters, accepting that you can never change the link afterwards.
Does it work through a phone case?
Usually yes with a thin case. Metal plates, magnetic mounts and card holders in the case can block it entirely.
Do you write the links for us?
Yes, on request. Send the final URLs with the order and we encode and verify each card before packing. Without that instruction, cards ship blank.
Next step
Send the spec. Get a price in one working day.
Give us the product, the quantity, the chip or stock and the destination country. We reply with unit price, tooling cost if any, and a production date.
Or email directly — a person reads it, not a queue. ethan@henghaomai.com