Check Any Tag We Mint

NFC Proof is free, runs on iPhone and Android, and needs no account or sign-up. It is read-only and writes nothing to any tag. Hold your phone to a tag, the chip answers with a one-time code, our service checks it against the tag’s counter, and a plain verdict comes back. The app also verifies the chip’s NXP factory signature on your device, a check a browser tap cannot perform.

The NFC Proof app showing a Valid Tag verdict with the minted record and an ECC IC Status

How It Works

Step 1

Tap the Tag

Open the app and hold your phone near the tag. There is no account and no setup. NFC Proof is read-only from the first tap to the last, and it writes nothing to any tag, ever. Any iPhone or Android phone with NFC can run the scan, and the tag needs no preparation of its own.

Step 2

The Chip Proves Itself

The app reads the chip’s NXP ECC originality signature and verifies it on your device against NXP’s published public key, which shows the silicon came from NXP. It then reads the tag twice, 200 ms apart. The counter must increment and the one-time code must change, so a static copy does not pass. Both codes go to our service, which redeems them against the tag’s monotonic counter and rejects any code already used.

Step 3

Read the Verdict

The verdict comes back as a colored band you can read at a glance. Validation sends the scan data to our service, and our privacy terms cover that processing. With Save Scan History on, every check lands in a log grouped by tag and exportable as CSV. That history stays on your phone. These checks concern the tag and chip, not the item carrying the tag.

The App

The Scan tab showing the Ready to Scan panel and the Scan NFC Tag button — The Scan tab waits with one button, and a tap starts the check.

A Valid Tag verdict sits above the record we minted for the tag and an ECC chip status.

A result for Example Sealed Product showing an ECC IC Status and a Sealed seal state read from a TagTamper tag — On a TagTamper tag the result adds the seal state, read off the chip on this scan.

The Scan Log tab listing previous checks grouped by tag — The Scan Log tab keeps every check you have run, grouped by tag.

The Guide tab with panels covering scanning, results, IC Status, and tamper detection — The Guide tab explains each part of a result inside the app.

Browser Tap or App Scan

You do not need an app to check one of our tags. Tap it with any modern phone and the chip writes a fresh single-use code into the link it hands your browser. Our service checks that code against the tag’s monotonic counter and rejects a code that has already been redeemed. That is a real cryptographic check, not a lightweight preview.

Capability	Browser Tap	In the App
One-Time Code Checked on Our Server	Yes	Yes
Factory Signature Checked on Your Phone	No	Yes
Automatic Double Check in One Scan	No	Yes
Seal Condition Read Live on TagTamper (TT) Seals	No	Yes
Saved Scan Log With CSV Export	No	Yes

Tap the tag again and the chip issues another fresh code, and the counter moves forward again. What a browser tap cannot do is talk to the chip directly, so it never verifies the factory signature and never reads a seal. If we switch a tag off for a report of fraud or theft, a legal order, or a security problem, every scan of it then shows Validation Disabled.

If you check tags often, the app does the rest of the work for you. One scan runs the double read, verifies the chip’s factory signature on your phone, reads a seal where the chip carries one, and saves the result to your log. The browser tap is for anyone, anywhere, with nothing to install. The app is for people who want the whole toolbox in a single scan.

How to Read a Result

The Verdict Band

The colored band is the tag-level verdict. Its four values are Valid Tag, Replay Detected, Warning, and Validation Disabled.

The Validation Row

The Validation row sits beside the UID and the counter. Valid means the scan passed, whether you used the app or a browser. Verification of the physical chip is a separate check, reported in IC Status. Valid does not describe that chip check.

The IC Status Chips

IC Status reports verification of the physical chip separately from the scan result. Its three values describe different chip checks and findings.

ECC: The app verified the chip’s NXP factory originality signature on your device against NXP’s published public key.
Secure: A Secure tag proved itself with its live key on that scan.
Not Evaluated: The chip check has not run yet, which is the state a browser tap leaves behind. It needs to pass only once per tag.

On NTAG 424 DNA TagTamper (TT) chips the result also shows the seal state, Sealed or Opened, read live off the chip on every scan. NFC Proof suppresses the seal chip for TamperKit tags, whose record and tamper history belong to the TamperKit app.

Keep four things apart when you read a result. The scan-data check says the code was fresh and was redeemed. The chip evidence says the silicon answered for itself. The tamper wire says whether the seal is still closed. None of the three speaks to whether a descriptive record on the tag is true, or whether the tag still sits on the item that received it.

One Reader for Four Families

NFC Proof is the general-purpose reader of the family; TamperKit, OnceMark, and StampCats are the writers, and every tag they touch checks out here.

NFC Mint Tags and Collectibles

A plain NFC Mint tag or collectible shows the record we minted for it, with the series, set, brand, and serial alongside the verdict. What you see is what we wrote at the mint, and nobody has changed it since.

TamperKit Tags

A TamperKit tag validates as genuine and shows identity only. Its record and its tamper history belong to the activator and stay private to the TamperKit app, so NFC Proof shows the verdict and stops there.

OnceMark Tags

An OnceMark tag validates as genuine and shows the public record its maker wrote once, rendered in a clearly marked Third-Party Metadata box. We guarantee a set record has not changed since it was written. We do not review or vouch for what it says.

StampCats Tags

A StampCats tag shows its family badge and validates like any tag we mint. Collecting stamps is the StampCats app’s job, so the passport and the places live there rather than here.

Free to Use

NFC Proof is free on the App Store and on Google Play. There is no account, no sign-up, and nothing to buy inside the app. It is read-only, so it writes nothing to any tag and changes nothing on one. Anyone holding one of our tags can check it, whether they bought the item or are thinking about it.

Support

Write to support@nfcmint.com and a person will answer. If you want to know what a particular result, status, or counter value means, Result Help explains every one of them. If a scan will not complete, check Service Status for the current state of the validator.