How NFC business cards actually work

The chip

NFC stands for Near Field Communication. The chip in a business card is almost always an NXP NTAG series tag (NTAG213, NTAG215, or NTAG216). The numbers refer to memory capacity:

• NTAG213: ~144 bytes usable
• NTAG215: ~504 bytes usable (the sweet spot for business cards)
• NTAG216: ~888 bytes usable

For a URL, 504 bytes is overkill. A typical Dyve URL is about 35 characters. We recommend NTAG215 anyway because it's only marginally more expensive than 213 and the extra headroom makes the chip more useful if you ever want to reuse it for something else.

The chip has no battery. It powers itself off the radio field generated by the phone's NFC reader, which is why you have to hold the phone within an inch of the card.

What's actually written to it

NFC chips store data in NDEF format (NFC Data Exchange Format). NDEF is a small container with typed records. The most common record type for business cards is a URI record. We write one URI record: https://cards.dyvetech.com/c/abc123. That's it. No app metadata, no auth, no payload. Just a URL.

The chip can also be locked after writing, which prevents anyone from overwriting the URL. We don't lock by default because it's nice to be able to reuse a chip if you change your mind, but locking is one extra step in NFC Tools.

What the phone does on a tap

When a phone's NFC reader detects a chip in range:

1. The phone reads the NDEF record(s) from the chip
2. It recognizes the URI record and identifies the protocol (https://)
3. It hands the URL to the default browser, which opens the page

On iPhone, this works on iPhone 7 and later, with background NFC reading turned on by default in iOS 13+. The first time it's a notification banner; tap the banner to open. On modern iPhones it often skips the banner entirely.

On Android, it's been smooth since 2012. The browser opens immediately.

No app is required on the recipient's phone because URL handling is a core OS feature. This is the whole reason NFC business cards work as a product: every smartphone shipped in the last 8 years already has the recipient side built in.

What our server does

When the chip URL opens, our server gets a request to /c/abc123. We look up which profile that short code currently points at, render the profile, and serve it back. The whole round trip is under 200 milliseconds.

The Save Contact button on the profile downloads a vCard file (.vcf), which is the standard contacts format that iOS and Android both recognize. The phone opens its native Add to Contacts flow with all your fields pre-filled.

Because the chip is just pointing at our server, you can update your profile any time and the next tap shows the new info. Same card, new bio.

The practical limits

• NFC range is about 1 cm. The phone basically has to touch the card. This is by design (security through proximity) but it does mean you can't tap from across the table.
• Metal blocks NFC. If you put a Dyve card on a metal surface or behind a metal phone case, taps fail. Cards in pockets, wallets, lanyards: fine. On a steel desk: maybe pick it up first.
• The chip is read-only after locking. The URL is permanent in the sense that you can't change what bytes the chip stores without a writer. But our system lets you change who that URL resolves to, which is what actually matters for business cards.
• NFC isn't the only path. Every Dyve profile also gets a QR code and a shareable link. If someone's phone is dead or they have an older device, the QR works the same way.

Why not just AirDrop?

AirDrop is fast and slick but only works between two iPhones, requires both phones to be unlocked and in range, and doesn't leave a card on the table that someone can tap five minutes later when they remember to. NFC cards are universal and asynchronous. You hand them out at a conference and they keep working long after.