How it works
Reads, writes and locks NFC tags straight from your phone's browser, with no app to install. When scanning it shows the tag's serial number and every NDEF record separately, with its type, size, language, MIME type and the hexadecimal dump of the raw content.
To write you can combine several records in a single message: text with its language, links, arbitrary MIME content and your own external types. It also includes helpers that build the content for you: vCard contact, email with subject and body, phone call, SMS, geographic coordinates, WhatsApp chat and opening an Android app.
All communication with the tag happens on your device through the Web NFC API: the content you read or write is never sent to a server. Today that API is only available in Chrome and Edge for Android, over HTTPS connections and with NFC enabled in the system.
Examples
https://ittools.techrecordType: "url" — 21 bytesA URL record compresses the well-known prefix (https://) into a single byte, so it takes up less than the text suggests.com.spotify.musicrecordType: "android.com:pkg"The Android Application Record opens the given app when the tag is tapped and offers to install it if it is missing.ejemplo.com:configrecordType externo — payload libreExternal types use your own domain as a namespace and are meant for data that only your own application understands.Use cases
- See what a tag really contains before tapping it: destination URL, contact, text or binary data.
- Write business cards with a vCard contact that is added to the address book with a single tap.
- Prepare stickers with the URL of a menu, a form, a how-to guide or the guest Wi-Fi.
- Test during development how an application reacts to different types of NDEF record.
- Leave a tag read-only once the content is final and you do not want anyone to change it.
Frequently asked questions
Why does it not work on my computer or my iPhone?
The Web NFC API is implemented only in Chrome and Edge for Android 8 or later. On desktop, in Safari and in the iOS browser it does not exist, so no web page can read or write tags. Open this tool from an Android phone with Chrome and over HTTPS.
What is the difference between a text record and a URL record?
The text record stores plain content along with its language and triggers no action: the system simply displays it. The URL record stores an address and makes the phone offer to open it; it also compresses the usual prefixes, so it takes up less space on the tag.
How much content fits on a tag?
It depends on the chip: an NTAG213 —the most common one in cards and stickers— has about 144 usable bytes, an NTAG215 about 504 and an NTAG216 about 888. The tool calculates the estimated message size while you build it and warns you when it exceeds the smallest chip.
Can the tag lock be undone?
No. Locking a tag activates a physical protection on the chip that leaves it read-only permanently: no device or app can write to it again. Use that option only when the content is final.
What is an external type and when is it worth using?
It is a record whose type is written as “domain:name” —for example example.com:config— and uses your own domain as a namespace. It is meant for data that only your application interprets: other readers see the record but do not try to act on it.
Is the tag content sent to any server?
No. Reading and writing are handled by the browser itself against the phone's hardware; neither the content you read nor the content you write leaves your device. The browser asks you for NFC permission the first time and you can revoke it whenever you want.