What is an NFC tag in simple terms?

An NFC tag is a tiny passive chip with an antenna, no battery required. When an NFC-capable phone comes within 1–4 cm of the tag, the phone powers it briefly and reads whatever data is stored on it — usually a URL that opens automatically.

How do I program an NFC tag?

Install NFC Tools (free on iOS and Android), open it, tap 'Write → Add a record → URL/URI', paste your destination URL, then hold the phone against the tag until the app confirms. With Taproo you can write a Taproo short URL once and re-target the destination later from your dashboard — no re-writing required.

How do I scan an NFC tag?

On iPhone XS or newer, just unlock the phone and hold the top-back of the device against the tag. On Android, unlock the phone and hold the back-centre against the tag. The link or action appears as a notification or opens directly.

Why won't my NFC tag read?

Three usual causes: the tag is below the phone's NFC antenna (try sliding the phone around), the tag is on a metal surface without a ferrite shield, or the tag was written with an unsupported record type. Re-write the tag as a plain URL and try again on a non-metal surface.

Can I lock an NFC tag so nobody can overwrite it?

Yes. Most writer apps have a 'Lock tag' option that makes the chip read-only forever. Lock tags that live in public (signage, products). Don't lock tags you might want to re-target — Taproo dynamic destinations remove this trade-off because the tag URL never changes.

Yes. NFC tags are passive — they only respond when a phone is held within ~4 cm. They can't track you, drain your battery, or push content to your phone unprompted. The phone always shows a confirmation before opening a URL or running an action.

Will an NFC tag work through a phone case?

Almost always yes. Standard plastic, leather and silicone cases pose no problem. Thick metal cases or wallets with magnetic clasps can block the signal — remove the phone from the case to test if a tag fails to read.

What is an NFC tag? How they work & program one

What an NFC tag actually is

NFC stands for Near Field Communication — a short-range wireless standard that lets two devices exchange data when they're held within about 4 cm of each other. An NFC tag is the passive half of that exchange: a postage-stamp-sized chip with a thin copper antenna, no battery, and a few hundred bytes of memory.

When an NFC-capable phone comes near the tag, the phone's antenna induces a small current in the tag's coil — enough to power it briefly and read its data. That data is almost always a URL, which the phone opens automatically.

You'll find NFC tags inside contactless bank cards, hotel key cards, transit passes, ski passes, festival wristbands, pet ID tags, business cards, and luggage labels. Anywhere you'd stick a QR code, you can use an NFC tag instead — and a tap is faster than aiming a camera.

How NFC works (in 30 seconds)

1. Power. Your phone's NFC antenna emits a 13.56 MHz radio field. The tag's coil absorbs just enough energy to wake up — no battery required.
2. Handshake. The tag sends back its UID and stored payload (usually an NDEF record containing a URL).
3. Action. Your phone's OS recognises the record type and opens the appropriate app — Safari/Chrome for a URL, Settings for Wi-Fi, Contacts for a vCard.

The whole exchange takes 100–200 ms. Because NFC has a maximum range of about 4 cm, it's almost impossible to trigger by accident — your phone has to physically touch (or near-touch) the tag.

How to program an NFC tag (5 steps)

1. Pick the right tag
Choose an NTAG213 (144 bytes) for short URLs, NTAG215 (504 bytes) for vCards or richer payloads, or NTAG216 (888 bytes) for the largest data. All three work with every NFC-capable iPhone and Android phone.
2. Decide what should happen on tap
Most people encode a URL — a vCard page, a Wi-Fi join page, a menu, a review prompt, or a feedback form. With Taproo you point the tag at a dynamic destination so you can change what it does later without re-encoding the chip.
3. Write the tag
Open an NFC writer app (NFC Tools on Android, NFC Tools or Shortcuts on iPhone), choose 'Write → URL/URI', paste your link, then hold the phone steady against the tag for 1–2 seconds until you see a confirmation.
4. Test before you deploy
Lock the screen, then unlock and tap your phone against the tag. iPhone shows a banner; Android opens the link directly. If nothing happens, re-write the tag and check the antenna alignment.
5. Lock the tag (optional)
If the tag will live somewhere public — a poster, a product, a pet collar — use your writer app to lock it read-only so nobody can overwrite your link.

Skip the writing step entirely. Every NFC tag from the Taproo shop ships pre-encoded with a dynamic Taproo link. Change the destination from your dashboard at any time — the tag itself never needs to be re-written.

How to scan an NFC tag

iPhone

iPhone XS and newer read tags in the background. Unlock the phone and hold the top-back of the device against the tag. iPhone 7, 8 and X need the NFC Tools app open.

Android

Most Android phones (Android 10+) read tags from the lock screen. Hold the back-centre of the device against the tag. Make sure NFC is enabled in Settings → Connections.

When a tag won't read

Antenna miss. Slide the phone slowly around the tag. Different phones have the NFC coil in different places.
Metal interference. A tag stuck directly to metal won't read — use an on-metal tag with a built-in ferrite shield.
Wrong record type. iPhones only auto-launch URI/URL records. If your tag was written as plain text, re-write it as a URL.
NFC turned off. On Android, check Settings → Connections → NFC. iPhones can't disable NFC system-wide, but some focus modes suppress the banner.

Frequently asked questions

Ready to build one? Pick a use case

Every option below ships as a free dynamic page plus optional NFC product.

Digital business card →Guest Wi-Fi tap →Menu & table talker →

See all 13 use cases →

Get an NFC tag that you can re-target any time

Every Taproo tag ships pre-encoded with a dynamic destination — change what it does from your dashboard, no re-writing required.

Browse NFC tags Back to Help Centre

What is an NFC tag?

What an NFC tag actually is

How NFC works (in 30 seconds)

How to program an NFC tag (5 steps)

1. Pick the right tag

2. Decide what should happen on tap

3. Write the tag

4. Test before you deploy

5. Lock the tag (optional)