Can You Rewrite NFC Tags?

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Key Takeaways:

  • NFC tags can be rewritten, but the process is not as simple as just rewriting text on paper.
  • Nintendo hardware checks if NFC cards are write-protected before allowing rewrites.
  • NFC tag data needs to be encoded properly for NFC devices to read it.
  • It’s recommended to back up NFC tag data before rewriting to avoid losing important information.
  • Not all NFC tags are rewritable – some tags like Datel PowerTags are exceptions.
  • NFC tags have limitations on the number of possible rewrites, usually around 100,000 writes.

What are NFC Tags and How Do They Work?

NFC stands for Near Field Communication, a wireless technology that allows data transfer between devices that are in close proximity, usually less than 4cm apart. NFC tags are small microchips that can store small amounts of data, usually between 96 to 8,192 bytes.

When an NFC-enabled device, like a smartphone, is brought near the NFC tag, it powers the tag’s microchip using electromagnetic induction. This allows the tag to send its stored data to the device. This data can include anything from simple text strings to URLs, contact information, Wi-Fi passwords, and more.

NFC tags are commonly used for contactless payments, transit ticketing, product authentication, interactive marketing, and automating smartphone tasks. Overall, NFC tags enable convenient, touch-based interactions between devices and the physical world.

Can You Rewrite Information on NFC Tags?

Yes, the data stored on NFC tags can be rewritten. However, there are some important factors to consider:

Nintendo Hardware Checks for Write Protection

For NFC cards used with Nintendo gaming hardware like the Nintendo Switch, the console first checks if the card is write-protected before rewriting it.

Nintendo uses NFC tags in the form of amiibo figurines and cards that can store data to unlock bonuses in games. If the card is not write-protected, Nintendo hardware can rewrite the data on it.

According to a study by researchers at the University of Adelaide, around 25% of common NFC tags they tested did not have write protection enabled by default. So for Nintendo hardware, rewriting unprotected NFC cards is possible.

NFC Tag Data Needs Proper Encoding

While the stored data on NFC tags can be changed, it’s not as simple as just overwriting it like text on a piece of paper. The information is encoded in a specific format that NFC devices can recognize and understand.

For example, a smartphone needs to encode the data in a standard like NDEF (NFC Data Exchange Format) for it to be readable when the tag is scanned again. Otherwise, the phone will not be able to make sense of the overwritten data.

Backup Data Before Rewriting

It’s generally recommended to back up the original data stored on an NFC tag before attempting to rewrite it. This provides a restore point in case something goes wrong with the rewriting process and important data gets lost.

Apps and tools designed for reading/writing NFC tags will usually provide options for saving a digital copy of the tag’s contents as a precautionary measure.

Not All Tags Are Rewritable

While most NFC tags are capable of being rewritten, there are some exceptions. Certain NFC tags are designed as “read-only” and cannot have their data changed.

For example, the popular NTAG213 NFC chip by NXP Semiconductor does not support rewriting once user data has been written to it. The microchip is configured to be write-protected after the first time data is stored.

However, some NFC tags like the Datel PowerTags are specifically engineered to be rewritten multiple times. So the rewritability depends on the specific NFC product and integrated circuit being used.

Rewrite Limitations

Even with rewritable NFC tags, there are hardware limitations on the maximum number of times the data can be changed. Most tags can reliably handle around 10,000 to 100,000 rewrite cycles.

The reason is that the rewriting process requires applying an electrical charge to the tag’s memory cells to change their binary state. Doing this repeatedly degrades the oxide layer insulating the cells, eventually leading to failure.

So while possible, rewriting NFC tags is not meant to be done infinitely – the recommended limit is around 100,000 writes depending on the tag’s integrated circuit.

How Does the Rewriting Process Work?

The specific steps involved in rewriting data on an NFC tag can vary based on the device, operating system, and tools being used. But in general, the workflow follows this basic procedure:

  1. Read the original data from the NFC tag using a smartphone app or NFC reader device.
  2. Optionally back up the data to a computer as a digital file.
  3. Write the new data to overwrite the original data in the app or via the NFC writer tool.
  4. Ensure the new data is encoded properly in NDEF or other compatible format.
  5. Bring the smartphone or writer device near the NFC tag to transmit the new encoded data.
  6. Verify the tag now contains the updated data by scanning it again with the smartphone.

Here are some best practices when rewriting NFC tags:

  • Avoid excessive writes that approach the tag’s rewrite cycle limit.
  • Use apps/tools from reputable developers and configure security options when available.
  • Double check that the new data is encoded properly in NDEF or other supported format.
  • Scan other devices against the tag after writing to check readability.
  • Consider write-protecting the tag after updating to prevent unintended changes.

FAQs About Rewriting NFC Tags

Here are some common questions about rewriting data on NFC tags and cards:

Can I Rewrite amiibo NFC Cards for Nintendo Switch?

Yes, as long as the amiibo card is not write-protected, you can rewrite the data on it and reuse it. The Nintendo Switch performs a check for write protection first and will block rewrites if enabled.

Be sure to back up the original data first in case you want to restore it later. Use an appropriate app or NFC card writer to overwrite the amiibo card with new data formatted correctly.

How Many Times Can NFC Tags Be Rewritten?

Most NFC tags can reliably handle around 10,000 to 100,000 rewrites, after which the performance degrades. The exact rewrite cycle limit depends on the integrated circuit and memory technology used in the specific NFC product.

Excessively rewriting NFC tags well beyond the rated cycle count can lead to failure and data loss. It’s best to stay well below the maximum limit.

Is Special Equipment Needed to Rewrite NFC Tags?

In most cases, only a smartphone with NFC support is required. NFC tag apps allow reading, writing, and encoding new data. Special NFC encoder/writer hardware can also rewrite tags but is not essential for basic usage.

Can NFC Tags Be Rewritten to Different Data Types?

Yes, you can rewrite an NFC tag that originally stored a text string to instead contain a URL, contact info, or other data type. As long as the new data is properly formatted and encoded, the NFC tag can change its purpose when rewritten.

How Can I Protect NFC Tags from Accidental Rewrites?

Some NFC tags support write-protection to avoid unintentional changes. Options include physically switching the tag to read-only mode, using software write-protection, or password-protecting writes.

Check your specific NFC tag’s capabilities to see which write-protection options are available. Write protection gives you greater control over data integrity.

What Happens if Writing New Data Fails?

If the attempt to write new data to an NFC tag fails, the tag will simply revert back to its previous data. The original data remains intact in the event of a failed write.

However, if the tag’s memory cells get corrupted during a partial write, irreversible data loss can occur. This is why backing up original data is highly recommended.


In summary, NFC tags can be rewritten with some special considerations – Nintendo’s write protection system, proper data encoding, backup needs, tag compatibility, and rewrite limits. The process involves overwriting existing data with new encoded information using a smartphone app or NFC writer. With a basic understanding of how rewriting works, NFC tags can be updated while avoiding pitfalls like data loss or corruption. Leveraging rewritability opens up additional use cases for NFC tags.

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