Provenance StoryTag an item

Toolkit

Choosing the right NFC chip

Not all tags are equal. The chip you choose decides whether a tag merely shares information — or can prove the object is the original.

ChipUser memorySecurityBest for
NTAG 213144 bytesNone (password option)Low-cost labels, links to public info
NTAG 215504 bytesNone (password option)General-purpose tags
NTAG 216888 bytesNone (password option)Longer stored data
NTAG 424 DNA~416 bytesAES-128, unique message per tap (SUN)Authentication of valuable items
NTAG 424 DNA TagTamper~416 bytesAES-128 plus tamper loopSeals, closures, memorabilia
ICODE SLIX (ISO 15693)VariesLimitedLonger read range; libraries, archives

Memory and security figures from NXP data sheets [1][2], last verified 2 November 2026. Always confirm with your supplier.

Why "secure" NFC matters

A standard NFC tag simply stores a web address. Anyone with a phone app can read it and write the same address to a new tag — a perfect clone. That is fine for sharing information, but useless as proof.

Secure chips such as NTAG 424 DNA hold a secret key that never leaves the chip. On every tap they add a fresh, encrypted code to the link (NXP calls this Secure Unique NFC, or SUN). The server checks the code and the tap counter, so a copied link or cloned tag fails verification.

Form factors

Placement and conservation

Never attach a tag to an original surface. Use reversible, acid-free adhesives on non-original material, and record the tag's position in the item's record so a conservator knows where it is. Metal, foil and liquids block NFC, so test the read from the outside before fixing a tag in place.

Encoding and testing

  1. Write the item's unique link (ideally a GS1 Digital Link-style URL) to the tag.
  2. Configure secure messaging if the chip supports it.
  3. Lock the tag against rewriting.
  4. Test with several iPhone and Android models.

SmartLinks supports QR, standard NFC and secure NFC on the same identity. Compare carriers in QR vs NFC, or follow a journey such as provenance for artists.

Sources

  1. [1] NXP, NTAG 213/215/216 product data sheet

    User memory of 144, 504 and 888 bytes; optional 32-bit password

    Last verified:

  2. [2] NXP, NTAG 424 DNA (NT4H2421Gx) product data sheet

    416 bytes user memory, AES-128, Secure Unique NFC (SUN) messages; TagTamper variant

    Last verified:

  3. [3] GS1 Digital Link standard

    Product identifiers expressed as web URLs in QR codes

    Last verified:

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Give your collection a digital identity

SmartLinks connects physical objects to a living digital record — one identity per item, readable by QR or NFC, with ownership history, documents and media that travel with it.

Questions

Frequently asked

Which NFC chip is best for authentication?+

A chip that produces a cryptographic, per-tap message, such as NXP NTAG 424 DNA. Each tap generates a unique code that a server verifies, so a copied tag is detected.

How much memory do I need?+

Very little. For provenance the tag only stores a link to the online record, which fits easily even on the smallest NTAG 213 (144 bytes of user memory).

How long do NFC tags last?+

NFC tags have no battery and are powered by the phone's field, so a well-protected tag can last many years. The adhesive and the environment usually limit lifespan more than the chip does.

Can I lock a tag so it cannot be rewritten?+

Yes. Most NTAG chips can be permanently locked after writing. Secure chips like NTAG 424 DNA additionally protect their keys so the authentication cannot be copied.