Writing NFC tags with a smartphone.

Adrian Kingsley-Hughes

One of my favorite technologies is NFC.I'm blown away that I can write datatoa little chipandthen access that using a smartphone or tablet. I've embedded NFC tags into all sorts of things, from documentstobusiness cards to 3D-printed objects.

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And it's easy!

What you need

You need two things:

• NFC tags: These come in all sorts of shapes and sizes, fromstickers to keychain disks to plastic cards . I go forNTAG215 compatible tags , because these are widely available, cheap, have enough on-board memory for my needs (504 bytes ought to be enough for anybody), and they have a data-retention lifespan of at least 10 years or 100,000 writing/rewriting cycles. You can findNTAG213 NFC tags that are cheaper, but these are limited to 137 bytes, and I've had website URLs that exceed this length.

The NTAG215 stickers are cheap and perfect for disposable applications.

Adrian Kingsley-Hughes

• NFC reader/writer app: I use NFC Tools, an app that's available for bothiOS and Android .

The NFC Tools app is perfect for small-scale NFC tag writing.

Adrian Kingsley-Hughes

How to create an NFC tag

Writing a few dozen tags with a smartphone app is fine, but if you find yourself wanting to write a lot, you're moving into the realm of an industrial setup like theSato CT4-LX .

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You have the tags, the app is installed, and you're ready to write your first tag. To write a tag that opens a webpage, tap Write, then Add a record, tap URL/URI, enter the address of the web page you want to open in the box, and tap OK.

NFC Tools app is packed with features.

Adrian Kingsley-Hughes

Now to write that to the tag: tap Write, bring the tag to the back of the smartphone, and it should detect the tag and write the data to it.

It's that easy!

How to test your NFC tag

To test the tag, exit the app, bring the tag up to the back of the smartphone, and it should be picked up and offer to take you to the web page.

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But you're not done. Remember that NFC tags are rewritable, and you don't want others fiddling with tags you've placed on things, as this could be a big security issue.

You have two options, both available in the NFC Tools app. You can password-protect the tag, or you can lock it.

Locking a tag is quick and easy -- and a one-way street! No undo if you want to reuse the app.

Adrian Kingsley-Hughes

With stickers, I tend to lock these, as it's quicker (you don't need to create or remember a password), but for reusable tags and cards, the password option allows for future reuse.

Password protecting a tag allows it to be re-written in the future, but prevents unauthorized tampering.

Adrian Kingsley-Hughes

The choice is yours, but you need to do one or the other to protect the tag from being altered.

Also: How to find out if an AirTag is tracking you - and what to do about it

And there you are. Done. Working with NFCs is that easy.

Pro tip: A handy way I use NFC tags

You can create an NFC tag to share your Wi-Fi password. If you want to do this, in NFC Tools, you'd add a record for Wi-Fi Network and enter the details for your network. I find this a super handy way to share the password for my guest Wi-Fi.

Also: The best Bluetooth trackers: Expert tested

Experiment with what the app offers -- there's a lot in there!

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