Your Mark. Written Once.

OnceMark tags contain a secure NFC chip that generates a new cryptographic code on every scan. Write your product's record onto the tag once, permanently. Anyone who scans it sees a genuine tag and the record you wrote.

See How It Works Read the FAQ

Wet Tag

Tamper Seal

See It in Action.

The OnceMark app ready to scan a tag — Tap any OnceMark tag to check it.

Writing a product record in the OnceMark app — Writing the record in the OnceMark app.

A genuine OnceMark tag showing the maker's record — What a buyer sees on scan.

The full OnceMark record on its own screen — The record at full length, on its own screen.

The OnceMark app's list of issued tags — Every tag you have issued, kept on your device.

How It Works.

Step 1

Write the Record.

Tap an unused tag in the OnceMark app and write your product's record: a title, a serial, a batch, notes. It is written once and becomes sealed and immutable. No codes, no sign-up: holding the tag is the only key.

Step 2

Attach It.

Fix the sticker to your product, or seal its packaging with a TagTamper (TT) label. Your record travels with the item. Every scan is verified on our servers and its time is fixed by an independent timestamp authority.

Step 3

Anyone Verifies.

A buyer taps the tag with any NFC phone and sees two things: the chip is genuine, and the record you wrote, attributed to you as its author. On a TagTamper (TT) label the seal status shows intact, opened, or opened-and-re-glued.

Two Variants.

Capability	Standard	TagTamper (TT)
Cannot be copied, photographed, or reprinted.	Yes	Yes
Identifies the exact unit, not just the model.	Yes	Yes
Independently timestamped scan history.	Yes	Yes
Chip-recorded proof the seal was ever opened.	No	Yes
Detects a re-glued or re-taped seal.	No	Yes

The TagTamper (TT) variant is a 25×50 mm tamper-evident label built on the NXP NTAG 424 DNA TT chip. Its tamper loop runs through the label's tail, which you place across the packaging opening. On every scan the chip reports two facts inside its cryptographically authenticated response: whether the seal has ever been opened (recorded permanently the moment the chip is powered with a broken loop) and whether it is open right now. A seal that was cut and glued back reads "opened, currently closed." Choose TagTamper (TT) when your product ships in packaging that should arrive unopened; the standard 25 mm round sticker covers everything else.

A peeled TagTamper (TT) label stamped VOID — Peeling or tampering with a TT label voids it. The chip burns in the broken loop permanently when the seal is broken.

Specifications.

	Standard	TagTamper (TT)
Chip.	NXP NTAG 424 DNA	NXP NTAG 424 DNA TT
Label size.	25 mm round	25×50 mm (D×L), tamper-evident material
Tamper detection.	—	Once-opened (permanent) and current-status loop detection
Protocol.	ISO/IEC 14443-A, NFC Forum Tag Type 4 — 13.56 MHz, read range up to 10 cm
Cryptography.	AES-128 with SUN message authentication on every read; ECC originality signature; random ID and encrypted UID privacy options
Endurance.	50-year data retention; 200,000 write cycles; operating range −20°C to 50°C

A Record Anyone Can Read.

Your record is public by design. Every scan shows it, rendered live from our database and attributed to you as its author, so your buyers do not need an app, an account, or your word for it. What they see is exactly what you wrote, and the chip's per-scan cryptographic code proves the tag it came from is genuine.

Behind it, every scan is verified server-side and written into a hash-chained log. The chain is anchored hourly with an RFC 3161 timestamp from an independent authority, so the history cannot be rewritten after the fact. Not by anyone else, and not by us.

Verify a Record

Frequently Asked Questions.

Who can see my record?

Everyone. That is the point: OnceMark records are public product records, shown to anyone who scans the tag. Write only what you want the world to read. If you need a private record instead, that is our TamperKit product.

Can I edit or delete a record later?

No. A record is written once and sealed permanently. That immutability is what makes the record credible to a stranger: nobody, including you, can quietly change it after the sale.

Do I need an account or a code?

No. There is no login, no sign-up, and no code to type. OnceMark never collects who you are: physically holding an unwritten tag is the only key, and the first record written into it is permanent. You buy the tags and you are done.

What if a tag already carries a record when I open the pack?

Do not use it; that pack was opened before it reached you. Every pack ships physically sealed, and a tag can only be written once, so a pre-written tag is itself proof of tampering. Return the pack for a refund like any other damaged product.

How is OnceMark different from TamperKit?

Same secure chips, opposite audience. TamperKit is for sellers fighting return fraud: the record stays private to the activator and is disclosed only in a dispute. OnceMark is for makers marking their work: the record is public and every scanner sees it.

Can someone copy my tag onto a counterfeit?

No. The chip generates a fresh cryptographic code on every scan, so a photograph, a reprint, or a cloned NFC sticker fails verification. Each tag also identifies its exact unit, so one genuine tag cannot vouch for a production run of fakes.