DIY Brick: how to use an NFC tag as an app blocker on iPhone

Physical app blockers are one of the better ideas in this space. You tap your phone on a small object to lock your distracting apps, and you have to tap the same object again to unlock them. Leave the object at home, in a drawer or on a shelf, and the phone becomes quieter until you go back to it.

You can buy that as finished hardware, or build it yourself with an NFC sticker and an app. This guide explains how it works, which tags to buy, and when the finished product is worth it.

What Brick and similar devices do

Brick is the best-known example. It's a small battery-free device: you choose apps to block in the Brick app, then start a session by tapping your phone against the device. It uses NFC, the same short-range radio as contactless payment. When we checked in September 2026, Brick listed it at $59 and said it works with iPhones on iOS 17 or later and with Android. Other hardware blockers work on the same principle.

What you pay for is a well-made object and an app designed around it. What makes it work, though, is the idea: the unlock is somewhere else, not in your hand. That idea is not tied to any particular device.

Tenki is not affiliated with Brick or any other hardware maker mentioned here.

How an NFC app blocker works on iPhone

Every iPhone that runs a current iOS version can read NFC tags. An app blocker uses this in two steps:

1. Blocking. The app uses Apple's Screen Time system to block the apps and websites you picked. iOS shows its own shield screen instead of a blocked app. The app never learns which apps you chose; Apple hands it anonymous tokens.
2. The scan. When you start or end a session, the app opens the scan sheet ("Hold your iPhone near an NFC tag"). You hold the top of the phone to the tag. The app reads the tag's serial number, or a link stored on it, and compares it with the tag you linked earlier. Any other tag does nothing.

A blank tag is enough. Each NFC chip has its own serial number, so you don't have to program anything with a separate writing app.

Which tags to buy

• Chip: NTAG213, NTAG215 or NTAG216. These are the most common NFC tags and iPhones read them reliably. The number only changes the storage size, which doesn't matter here.
• Shape: stickers for walls, shelves and doors; key fobs if you want something to hand to someone; cards if you want it to live in a drawer.
• Metal surfaces: an ordinary sticker on a fridge or a metal door frame often won't read. Buy tags labelled "anti-metal" or "on-metal" for that.
• Price: a pack of ten stickers typically costs a few euros. Buy a pack; spares are useful.

Avoid tags sold only as "MIFARE Classic". They are common in older access systems, and iPhones handle them less reliably.

Setting it up

1. Stick the tag where you'll leave it. Before you link it, decide its place. Moving it later is fine, but its place is the whole design.
2. Create a blocking profile in your app: the apps, categories and websites to block. Include the websites of the apps you block, or the scroll just moves to Safari.
3. Choose the NFC tag as the way to start or end the session, and scan the tag once to link it.
4. Test it: start a session, try to end it without the tag, then with it.
5. Turn on strict mode if your app has it, so deleting the app mid-session isn't an easy exit.

Where to stick it

There is no single right place; put it wherever works for you. People use the inside of the front door, a bookshelf, the kitchen, a drawer on another floor, or their desk at work. A tag inside the front door has a nice side effect: you lock your apps as you come home, and you pass the tag when you leave.

One thing to know: a tag on your phone case, or on a keyring you carry in your pocket, travels with the phone, so ending a session takes a second. That can be fine for a short pause, less so for an evening you know will be hard.

DIY or hardware?

Hardware is a good choice if you want one object that feels like part of a ritual, or if you're giving it as a gift. A sticker makes sense if you'd rather spend the money elsewhere, want tags in more than one place, or want to find out first whether the idea works for you. Several apps support NFC tags, some free, some paid. Tenki is one of them, and we're biased; test the idea with whatever you have.

If you don't want to buy anything at all, start with paper. Our guide to QR code app blockers covers the free version, and the QR generator makes a random code in your browser.

Honest limits

• It's still your phone. Any blocker can be undone by someone determined, for example by changing Screen Time permissions or waiting out a timer. The tag doesn't make quitting impossible. It makes quitting a decision instead of a reflex, which is usually enough.
• Plan for being away. If the only tag is at home, you can't end a session from the library. Use a timer session on days out, or carry a second tag only on those days.
• Emergencies. Check what your app offers. Tenki has a small number of emergency unblocks for exactly that, and you only ever block what you chose.

How it works in Tenki

In Tenki, an NFC tag is one of three ways to end a session, with ending in the app and scanning a QR code. Link any NTAG sticker once, and choose how the session runs: Until you end it (blocked until you tap the tag), Timer, Pause by scan (a tap gives you a timed pause, a second tap during the pause ends it) or Short opens (a few brief opens per app). Tenki is free to try for seven days, then a one-time purchase of €7.99, with no hardware to buy and no subscription.

For the rest of the setup around the tag, from where the phone goes to how breaks work, read how to stop using your phone while studying.