How to use NFC tags with iPhone for home inventory

How additem.to uses NFC tags

Every NFC chip ships from the factory with a unique read-only ID, called a UID. additem.to reads that UID and stores a mapping inside the app: UID X is linked to "Workshop top shelf".

That UID mapping is the default, and it has real advantages:

• You can use any NFC tag from any pack without programming it first.
• Changing what a tag points to is a one-tap edit, not a re-write.
• A tag that has been used before by another app still works - the UID is permanent.

On top of that, there's an optional extra: Tap to Open. Turn it on for a writable tag and the app writes a small link to the sticker, so tapping it with your iPhone opens the linked item or location directly - even when the app is closed or the phone is on the lock screen. More on that below.

Read-only and pre-written tags both work

A side benefit of the read-UID approach: it doesn't matter what state the tag's writable memory is in. The following all work fine:

• Tags that have been hardware-locked by another app or sold pre-locked.
• Tags with other data already written to them - a URL to someone else's website, an NDEF record for a different app, a vCard, an old WiFi password. additem.to ignores the writable area entirely.
• Tags from leftover or clearance packs where you've no idea what was put on them.
• Tags given to you secondhand from a friend's drawer.

The UID is always readable, always permanent, and that's all the default linking uses. With most inventory apps that write to the tag, a locked or pre-programmed tag is dead stock - it can't be repurposed without somehow clearing it. Here you can use them as-is. The only thing a locked or read-only tag can't do is Tap to Open, which needs to write to the tag - everything else works identically.

If you haven't bought any tags yet, see the NFC tag buying guide first - which types to pick and which to avoid.

Linking a tag to a location (the most common case)

This is what 90% of your tags will be doing: marking a physical spot that holds things.

1. Stick the tag somewhere you'd naturally look when wondering what's inside - inside a cupboard door, on the front of a storage box, on the underside of the shelf above, inside the front of a drawer.
2. Open that location in the app. If it doesn't exist yet, create it first (Locations -> + -> name it).
3. Tap the NFC tag option on the location screen.
4. Hold the top edge of your iPhone within a couple of centimetres of the sticker. The NFC antenna sits behind the camera bump, not in the middle of the phone.
5. The app reads the tag's UID and confirms the link. That's it.

From now on, opening the app and scanning that sticker jumps straight to this location.

Linking a tag to an item

Less common, but useful for things that move around. The flow is the same, but you open an item instead and use the NFC tag option on the item screen.

Good item-tag candidates:

• Camera cases, lens cases, hard drives
• Test or measurement equipment that lives in a drawer most of the time but gets borrowed
• Loaned items - scan the tag to see who currently has it
• Bulky tools where you want a one-scan check-in / check-out

If you're not sure whether to use a location or an item tag, default to location. Locations are the framework of an inventory and item tags are the exceptions.

Using a linked tag: the scan flow

Once a tag is linked, jumping to it works like this:

1. Open additem.to.
2. Tap Quick Scan.
3. Hold the top edge of your phone over the sticker.
4. The app reads the UID, looks it up, and jumps straight to the linked location or item.

From there you can add or remove items, check what's there, check something in or out, or move on to scanning the next tag. Quick Scan stays available for repeated scans, which is what makes a stocktake or "what's on this shelf" sweep quick.

Some sections of the app - stocktake, pick lists, check-in / check-out - have their own scan button that does the same thing in context. The principle is the same everywhere: the app reads the UID, the app does the lookup.

Tap to Open: skip the app entirely

If your tags are writable (standard NTAG213, NTAG215, and NTAG216 stickers are), you can make a tap do everything. With Tap to Open enabled, the app writes a small link to the tag. From then on:

1. Hold your iPhone over the sticker - app closed, phone locked, doesn't matter.
2. iOS reads the link and shows a notification.
3. Tap it, and additem.to opens straight at the linked item or location.

You're offered Tap to Open when you first register a tag - one tap of the phone registers the tag and writes the link in a single step. You can also enable it later from the tag's detail screen, or disable it again (the app erases the link from the sticker).

Worth knowing:

• It needs a writable tag. If a tag turns out to be read-only or too small, the app registers it normally and just tells you Tap to Open couldn't be enabled. Nothing is lost.
• In-app scanning still works exactly the same on a Tap to Open tag - the UID link is untouched.
• Other NFC apps could overwrite the link on an unlocked tag. If that happens, relinking is a ten-second job; the in-app UID link is unaffected.
• It works offline. The link routes straight into the app on your phone - no internet involved.

Scan technique

Three things make a scan reliable:

• Use the top edge of the phone. The NFC antenna is behind the camera. Bringing the middle of the phone over the tag often misses.
• Get within a few centimetres. NFC range is short. You don't need to press hard, but you do need to be close.
• Hold for half a second. A flick-past can miss. A slight pause reads reliably.

When a tag won't read

If a scan does nothing, run through these in order:

• Phone position. Re-aim with the top edge of the phone over the tag. This fixes most failed reads.
• Metal surface. Regular NFC stickers don't work well on metal - filing cabinets, toolboxes, fridges. Either move the tag to a non-metal surface (the underside of a metal shelf often works) or buy anti-metal tags, which have a ferrite shield.
• Tag type. If you bought a generic pack that turned out to be Mifare Classic, it won't work with iPhone. Check the product details. NTAG213, NTAG215, and NTAG216 are the safe choices.
• Damaged tag. The chip inside thin stickers can be cracked by sharp bends or by being scraped against a screw head when you press the sticker down. If only one tag in a batch fails, it's probably that tag.
• "Unknown tag" message. If the scan succeeds but the app says it doesn't recognise the tag, that UID hasn't been linked yet (or has been unlinked). Open the location or item you want it to point to, choose the NFC tag option, and scan again.

Where this gets useful

Once you've tagged a handful of locations, the workflow changes. A few patterns people end up using:

• Workshop / garage: tag each shelf and drawer of a tool cabinet. Scan to log what you just put in or out without typing.
• Kitchen pantry: tag each shelf. Scan to see what's running low when you're writing a shopping list.
• Loft and storage: tag each box from the outside. Scan to see what's inside without unstacking everything.
• Camera or hobby gear: tag the case, link it to a kit. Scan to check everything's accounted for before you head out.

You don't have to tag everything. A few tags in the right spots covers the cases where you actually need speed - the rest of the inventory works fine without them.

QR codes and barcodes as alternatives

If a surface is metal, a tag is too small to find by touch, or you want to scan from across a room, a QR sticker works the same way. Each pre-printed sticker carries a unique code, and additem.to reads that code through the camera and looks it up the same way it looks up an NFC UID. QR codes generated by the app go one better: they open the item straight from the iPhone Camera, no app-opening needed. The app can also print QR and barcode label sheets on Avery templates - see the label printing guide.

Barcodes work too: link a product's own barcode to an item, or reuse labels from a previous system like Sortly. You can mix all three freely - NFC for instant taps, QR for boxes you scan from a distance, barcodes for products and existing labels. See the tag buying guide for cost and durability differences.