How NFC business cards work
The chip inside an NFC card sends a link when a phone comes close. This post explains where that link goes and why no app is needed.
What is inside the card
An NFC business card holds a small chip and an antenna. The chip carries a single piece of information: your card address. When a phone comes close it reads the address and shows a notification.
Why no app is needed
iPhones and Android phones understand NFC links at the operating-system level. Whoever taps the notification sees your card in the browser; there is nothing to install.
What happens when your details change
The address on the chip never changes; you update the page it opens from your panel. New phone number, new title, new portfolio: same card, new content.
Phones without NFC
The QR code on the back carries the same address. The camera app reads it and the same page opens.