Yes,Many NFC cards can be reprogrammed if the chip allows it and there’s still space in the user memory. Password-protected cards can accept changes after successful authentication. Cards intended for payments, travel, access control, and completed Amiibo cards have different requirements.
For business purposes, the ability to reprogram cards can be important from a budgetary and management perspective.
What Does Rewriting an NFC Card Mean?
Rewriting refers to changing the information stored in the card’s user memory, including URL, contact page, Wi-Fi entry, telephone number, email address, or text.
Phone-readable information follows the NFC Data Exchange Format (NDEF), which determines how the phone should respond after scanning. Rewriting doesn’t affect the chip type, memory capacity, factory-assigned UID, or other fixed details.
Which NFC Cards Can Be Rewritten?
Blank NFC Cards
Blank NFC cards intended for encoding are usually delivered in read/write mode. They can be encoded using a mobile device, desktop reader, or bulk encoder.
Previously Programmed NFC Cards
A programmed card can be reused as long as its memory remains writable and the new data fits within the available space. Salespeople can update their profile links on previously encoded cards.
Password-Protected NFC Cards
Password protection prevents unauthorized writing while still allowing approved rewrites after the correct password is entered.
Secure NFC Cards
Secure chips use passwords, file permissions, or encryption-based authentication. Hotel room cards can be reset using secure systems, but not by guests using a mobile application.
What Determines Whether an NFC Card Is Rewritable?
To rewrite an NFC card, it must be able to accept data in its writable memory. Also, you may need the correct password, sector key, or security key. The new information must fit within the available user memory on the card, and your device must be able to communicate with the specific chip type.
A failure to rewrite the information doesn’t mean that the card is permanently locked. Metal may affect the antenna, while bending may damage it. The same problem happens if the card is positioned incorrectly relative to the phone, an unsupported app is used, or the card is not NDEF-compatible.
Which NFC Chip Types Are Rewritable?
NTAG213, NTAG215, and NTAG216
These chip types can store information in user memory. They also offer optional password protection and locking features. These chips are used for review cards, menus, digital business cards, and marketing purposes.
| Chip | User Memory | Suitable For
|
| NTAG213 | 144 bytes | Short URLs, review cards, and menus |
| NTAG215 | 504 bytes | Longer links or several NDEF records |
| NTAG216 | 888 bytes | Large amounts of text or more complex NDEF records |
Choose the appropriate chip based on how much data you want to store.
MIFARE Ultralight
MIFARE Ultralight has writable memory, but password protection, counters, and locking features are optional. So, make sure you know the exact model.
MIFARE Classic
MIFARE Classic is divided into sectors protected by keys. Writing to a sector is possible only when you have the correct key. Some phones don’t support this chip.
MIFARE DESFire
MIFARE DESFire stores data in separate files with defined access keys. Only authorized software can write or update information in those files. This chip is good for access control, campus cards, and loyalty programs.
NTAG 424 DNA and Secure NFC Chips
NTAG 424 DNA and Secure NFC Chip offers AES authentication, secure messaging, and dynamic web links. It can store updated information, but it needs proper keys and system configuration.
Which NFC Cards Cannot Be Freely Rewritten?
Some NFC cards cannot be freely rewritten because of certain characteristics.
Permanently Locked NFC Cards
Locking makes some memory sections of an NFC tag read-only. Once applied, those sections cannot be unlocked using an ordinary phone or NFC reader.
Payment Cards
A phone can detect a contactless bank card but can’t write payment information to it. The payment card is controlled by the bank or issuer, which owns the chip, keys, and payment application.
Transit Cards
Transit cards can update their balance, trips, or tickets through approved operations. This is done by the transit company, not by an ordinary NFC writer.
Access Control Cards
Access control cards rely on access system keys, permissions, and back-end records. So, only the access control system can change the data and permissions.
Amiibo Cards
Amiibo cards use blank NFC NTAG215 chips with writable memory. Once Amiibo data is written, key sections are locked, making it impossible to change one Amiibo card into another.
Non-NFC RFID Cards
A phone’s NFC operates at a frequency of 13.56 MHz. Most 125 kHz and UHF RFID cards use different frequencies and protocols, so they can’t be rewritten using a phone’s NFC.
Password Protection vs. Permanent Locking
Both password protection and locking prevent unwanted modifications, but they do so differently.
| Point | Password Protection | Permanent Locking |
| Further Editing | Possible after authentication | Impossible |
| Changing the Settings | Possible if permitted by the chip and password | Impossible once locked
|
| Suited For | Editable content | Finalized content |
| Drawback | Forgetting the password | Locking incorrect content |
| Protection | Basic write protection | Irreversible write protection |
Password protection allows authorized personnel to edit the card. Still, it doesn’t conceal or encrypt a public URL saved on the card.
Locking turns the selected memory area into read-only memory. So people can scan and read the public information but can’t modify it.
Can a Locked NFC Card Be Unlocked?
This depends if the card has been locked. If a password has been used to lock the card, it may be unlocked if the password is known and the chip allows changes to its security settings. Once permanently locked, it’s impossible to unlock the NFC card.
Erasing the data stored on the card or changing the applications will not unlock the NFC card once it has been permanently locked.
How to Check Whether an NFC Card Is Rewritable
Scanning the card with suitable NFC software will display the chip type, NDEF properties, free memory space, and if the card is writable. All these factors determine whether the card is capable of storing new data or whether the specific writable area is accessible. Also, you may want to inspect the password, key, or any other information related to the lock.
The use of the card is another factor that should be considered. If the card is an open marketing card, it can receive a new NDEF message, whereas a staff card or transit card receives updates only from its issuing system.
How to Rewrite an NFC Card
When rewriting your card, make sure it belongs to you or that you have permission to do so. Back up the existing information if you need it soon.
How to Rewrite an NFC Card on Android
Enable NFC and launch the appropriate rewriting application. Scan the card to determine if it’s writable and has enough available memory. Then create your record, tap “Write,” and place the card close to your phone’s antenna. Scan the card again to make sure that the correct record opens.
How to Rewrite an NFC Card on iPhone
Create your record in the writing app, execute the writing command, and place the upper part of your iPhone close to the NFC card.
How to Rewrite NFC Cards With a Desktop Reader
Connect a reader that can rewrite that particular chip type and launch the software on your computer. Enter the data, write one card to make sure everything works, and only then proceed with the batch.
How to Encode NFC Cards in Bulk
When encoding cards in bulk, it’s important to use only one chip type and set up the proper data format, security settings, and verification process. Before the cards go into production, approve the sample cards and the data format.
Why Can’t I Rewrite My NFC Card?
| Problem | Cause or Solution |
| “Read-only” | The card is protected or locked |
| Authentication failed | Check your password or key |
| File is too big | Make it smaller or use another chip |
| Not detected by the phone | Move phone away from any metal or use a thinner cover |
| Can read but can’t write | Check your key, chip, and application support |
| Previous page opens | Clear your browser or cache |
| Stop writing | Keep your card stable and try again |
How Many Times Can NFC Cards Be Rewritten?
According to NXP, NTAG213, NTAG215, and NTAG216 chips are designed for 100,000 write operations. This figure applies to those specific chips, not to every NFC card. A write operation happens when you modify, delete, or save data on the tag. Scanning doesn’t normally count as a write operation, except when some internal data is incremented or updated.
Business cards, menus, and review cards generally wouldn’t exceed that number.
Does Rewriting an NFC Card Change Its UID?
No. It’s the contents of the user memory, such as a URL or contact information, that are rewritten. The factory UID doesn’t change because the chip manufacturer assigns it during manufacturing. Think of the UID as the serial number of the NFC card.
Is It Safe to Leave an NFC Card Rewritable?
When to Leave a Card Rewritable
Leave the card rewritable during setup, debugging, personal use, and limited campaigns where links may need to be corrected or content replaced.
When to Password-Protect a Card
Apply password protection to public cards that require updates by authorized personnel only. The password prevents unauthorized editing as letting future modifications.
When to Permanently Lock a Card
Apply a permanent lock once the content is finalized. Make sure to test the link on different smartphones and create a record of the encoded data before locking the content. For a large campaign, use a short URL stored on the card and then lock the card.
Which Rewritable NFC Card Should You Choose?
| Use Case | Recommended Tag |
| Review Card / Menu | NTAG213 |
| Digital Business Card | NTAG213 or NTAG215 |
| Updatable Public Card | Password-Protected NTAG |
| Product Authentication | NTAG 424 DNA |
| Access or Loyalty Program | MIFARE DESFire |
| Custom High-Volume Project | Supplier Encoding Service |
Select the tag according to your post-release use case. If links or data need to be updated later, make sure you retain that option. If individual tags require unique data, ask the supplier about the encoding process and batch testing.
Frequently Asked Questions
Can All NFC Cards Be Rewritten?
No. The chip must be writable, and the memory must not be permanently locked. Payment cards, transit cards, and secure access cards can usually be rewritten only by their issuing systems.
Can I Erase and Reuse an NFC Card?
Yes, if the user memory is still writable. If an NFC card is password- or key-protected, the correct credentials must be entered before erasing or writing data.
Can a Read-Only NFC Card Be Rewritten?
A permanently locked memory area can’t be restored using standard software. However, a password-protected card is different because write permissions can be restored after proper authentication.
Can I Rewrite an NFC Card With an iPhone?
Yes. A compatible iPhone model and NFC writing application can rewrite supported NDEF cards. Position the top of your phone close to the card until confirmation of the writing process appears, then scan the card again.
Can Android Rewrite NFC Cards?
Yes, if the phone has NFC and supports the chip in question. For password-protected cards, the correct password or key is required, along with software that supports the data format for non-NDEF cards.
Can a Password-Protected NFC Card Be Rewritten?
Yes. Enter the correct password or authenticate yourself in another approved way to obtain write permission for the card data.
Does Rewriting Change the UID?
No. Rewriting involves changing user data such as URLs, contacts, or Wi-Fi settings. The UID of the NFC card, which is set during chip manufacturing, doesn’t change.
Does Reading Consume Write Cycles?
A regular scan doesn’t consume user memory write cycles. A write cycle involves adding, erasing, or changing data. Scan counters may also generate internal write cycles.
Can NFC Business Cards Be Updated?
Yes. It’s possible to update the card without replacing it by rewriting the link to a website hosted elsewhere.
How Can I Prevent Someone Else From Rewriting My NFC Card?
If the card requires future updates, consider applying password protection. Otherwise, once everything on the card is finalized, you can lock it permanently.
Conclusion
Many NFC cards can be easily rewritten, provided that the memory is unlocked and the chip allows rewriting. The finest options depend on many factors, like your data capacity, need for updates, and required security measures.
At JLTRFID, we specialize in producing rewritable NFC cards according to your chip, printing, and security specifications.
