To write a URL to an NFC tag, install a writing app such as NFC Tools on your phone, choose Write, add a URL / URI record, type the link and tap Write, then hold the blank tag against your phone until it finishes. It works on Android phones and on iPhone 7 or newer. Test the tag on a second phone before you lock it or stick it anywhere permanent.
What you need
- A blank NFC tag. Stickers, cards and key fobs built on NXP’s NTAG213, NTAG215 or NTAG216 chips are the common ones. NXP’s product page says they “fully comply to NFC Forum Type 2 Tag” specifications, so phones read them without special software.
- Phone. Any Android phone with NFC works. On iPhone, WakDev’s NTAG213 reference says reading and writing through NFC Tools work from the iPhone 7 onward on iOS 15.6 or later, but you start the scan yourself in the app.
- Writer app. I use NFC Tools because its maker, WakDev, publishes the steps. Other writer apps work the same way.
- The final URL. Copy it from the address bar so you don’t introduce typos.
Steps to write the URL
These are WakDev’s own steps for writing a link with NFC Tools, the same on Android and iOS:
- Open NFC Tools and go to the Write tab.
- Tap Add a record.
- Choose URL / URI.
- Paste your link and tap Validate. Keep the https:// part.
- Tap Write / X Bytes. The number tells you how much space the record needs.
- Hold the tag against your phone and wait for the writing to complete. On iPhone, that’s the top edge near the camera.
For a business card, use a plain URL record. It’s the one record type every phone handles on its own.
Check that it worked
Don’t test with the phone you used to write. Grab a different one, ideally an iPhone if you wrote with Android, or the reverse.
On an iPhone XS, XR or later, wake the screen and tap the tag near the top. Apple’s tech talk on background tag reading says a notification pops up once the tag is read, and tapping it opens the link. For a normal web address, “Safari will handle all unregistered application links.”
If nothing appears, Apple lists the times the reader pauses: “a Core NFC reader session is in progress, Wallet or Apple Pay are in use, cameras are in use, or the device is in Airplane Mode.” Close the camera and try again before you blame the tag.
Mistakes that break the tag
Too many records. Some people add a URL, a phone number and a vCard to one tag. Apple says “only the first discovered URL record in the NDEF message will be processed.” Keep one URL record and nothing else.
The link is too long. An NTAG213 has 144 bytes of user memory. WakDev puts that at around 130 characters of URL, because common prefixes such as https://www. shrink to a single byte. A long tracking link with UTM tags can run out of room. NXP’s larger chips offer 504 or 888 bytes, but a short link is the better fix.
Locking too early. NFC Tools can lock a tag, and WakDev describes that lock as permanent and irreversible. Lock a tag with a typo in the link and it’s garbage. A 32-bit password, which NXP’s chips support, blocks other people from rewriting the tag and can be removed later.
Writing a contact instead of a link. Our post on whether NFC business cards work with iPhone explains why a vCard record on the tag does nothing on most iPhones.
Which link to write
Most tags end up on business cards, and the details on a card change: a new job title, a new number, a new company.
Write a link to a page you can edit. Never write the details themselves. The chip is rated for 100,000 write cycles according to WakDev, so rewriting isn’t a hardware problem. The problem is the tags you’ve already handed out, which you can’t rewrite.
On QRCard, that link is your vanity URL, qrcard.in/c/yourname. It fits on an NTAG213 with room to spare. Edit your profile and every tag you’ve already written shows the new details, so locking that tag is safe. Whoever taps it gets a Save Contact button that hands their phone a .vcf file. The NFC business card guide goes further.
The limitation: QRCard doesn’t sell NFC hardware. You buy the blank tags yourself and write them with an app as described above. And NFC only reaches people whose phones have it switched on and nearby, so print a QR code with the same link on the card too. How to make a QR code for your business card covers size and testing, and sharing contact info with a QR code covers what happens on the other person’s phone.
FAQ
Can I write an NFC tag with an iPhone?
Yes. According to WakDev, NFC Tools can read and write tags from the iPhone 7 onward on iOS 15.6 or later. You start the scan manually in the app, then hold the tag to the top of the phone.
Which NFC tag do I need for a URL?
An NTAG213 is enough for most links. It has 144 bytes of user memory, which WakDev puts at around 130 characters of URL. NTAG215 and NTAG216 hold more if your link is unusually long.
Should I lock the tag after writing it?
Only once you’ve tested it and you’re sure the link won’t change. Locking is permanent. If you might change the link later, set a password instead, which you can remove.
Why doesn’t my phone open the link when I tap the tag?
On iPhone, the screen must be on and the camera, Wallet and Apple Pay closed. Also check that the URL record is the first record on the tag.