How to block apps on Android with an NFC tag (step by step)

Short version: you install a free app, you tap your phone on a cheap NFC tag, and the apps you picked are locked until you tap the tag again. No account, no subscription, nothing leaves the phone. Below is the long version, including the parts people usually get wrong.

What you need

• An Android phone with NFC, running Android 14 or newer. Almost every mid-range and flagship phone from the last few years qualifies. To check: Settings, then search “NFC”. If the toggle exists, you’re fine.
• One NFC tag. Any standard tag works: NTAG213, NTAG215 or NTAG216. They come as round stickers, cards, or keyfobs. A pack of ten costs around €5 on Amazon or AliExpress. You only need one, but spares are useful (more on that below).
• Lock, free on the Play Store. Android only, open source (MIT).

If you don’t have a tag yet, you can start in manual mode and switch to a tag later. It works, but the whole point is the physical gesture, so order the tag.

Which tag?

They all hold a serial number your phone can read, and that’s all Lock uses. So the choice is about form, not specs:

• Round sticker (25 mm): almost invisible. Sticks under a desk, on the fridge, inside a cupboard door. My default.
• Card (credit-card size): bigger antenna, so the read is a bit more forgiving on phones with a small NFC zone. Fits in a wallet or a drawer.
• Keyfob: for people who want to carry it, which is a valid strategy if the “get up” part doesn’t suit you.

Two I use, if you want a direct link: a round sticky tag and a wallet-sized card. Those are affiliate links: if you buy through them, a small cut helps keep Lock free, at no extra cost to you. Any equivalent tag from another shop works exactly the same.

Avoid tags marketed for payments or transit (they’re locked to their own systems), and avoid “anti-metal” tags unless you’re actually sticking the tag on metal.

Setup, in order

1. Install Lock and grant the permissions. Lock asks for three things, and it explains each one on screen:

• Accessibility Service: this is how Android lets an app know that another app is opening. Lock uses it for exactly that: to notice you just opened a blocked app and send you back to the home screen. It doesn’t read screen content and doesn’t touch other apps’ data; the source code is public if you want to check. This permission is what makes the block impossible to swipe away, so it’s not optional.
• Display over other apps: to show the lock screen on top of the blocked app.
• Ignore battery optimization: so Android doesn’t quietly kill the service in the background. Without it, the block can silently stop working after a while.

2. Pick your apps. Choose the ones that eat your time, not everything. Three to six is a good start. Lock has categories (Social, Games, Tools) and a search box. Leave the things you actually need (Maps, banking, the messaging app your family uses). Blocking too much is the fastest way to end up using the emergency exit for legit reasons, and then it stops meaning anything.

3. Pair the tag. In Lock, choose “Add a tag” and hold the phone flat against the tag. The NFC antenna is usually near the top or the middle of the back of the phone; if it doesn’t read, move it slowly. Once it’s paired, Lock remembers that tag’s serial number. You can pair up to five tags (desk, home, wallet).

4. Set your safety nets. This is the step people skip. Two settings matter:

• Emergency unlocks: how many temporary unlocks you get per session, and how long each lasts (a few minutes). They reset every time you start a new session.
• Auto-unlock: after how long a session ends on its own. Default is a few hours. This is what protects you if you lose the tag or leave it at home. You can push it up to “never” if you want the strict version, but do that after a week, not on day one.

Uninstalling Lock always works, like any other app. That’s deliberate: a tool you can’t remove is a tool you can’t trust.

5. Lock. Tap the phone on the tag. Selected apps are locked. Try opening one: you’ll see the lock screen and get sent home. There is no button on it. That’s the feature.

6. Unlock. Go back to the tag, tap again. Done.

Where to put the tag (this is the actual trick)

The tag placement decides whether this works on you. Two rules:

If the tag is within arm’s reach of where you scroll, you have built a very elaborate “Ignore” button.

Not within arm’s reach of where you scroll. Nightstand tag, scrolling in bed: that’s the failure mode. Put it somewhere that requires standing up: the kitchen, the entrance, the bookshelf on the other side of the room.

In a place with a purpose. The gesture works better when unlocking means “I’m done with this block of time”, not “I gave in”. Some setups that people tell me work:

• On the desk at work, tag at home: phone locked for the whole workday. You unlock when you walk in the door.
• Under the kitchen table: unlock while cooking or eating, lock when you leave the kitchen. Evenings become quiet by default.
• Inside the wardrobe: lock in the morning while getting dressed. Unlock in the evening at the same spot. The two taps bracket the day.
• In the car: lock before you drive, tag stuck on the dashboard. Useful for people whose danger zone is the red light.
• Two tags: one at home, one at the office. Both unlock, both lock. Anywhere else, the phone is locked.

Avoid: your pocket, the phone case, your keychain if your keys live next to you. Carrying the tag is not wrong, but it defeats the “get up” part, and that part is most of the effect.

Things that go wrong, and fixes

• The tag reads on the second try, not the first. Normal. Phones differ in antenna position. Find the spot once, then it’s consistent. Cards read more easily than small stickers.
• The block stopped working after a day. Almost always battery optimization. Go to Settings, Battery, find Lock, set it to “Unrestricted”. Some manufacturers (Xiaomi, Huawei, some Samsung modes) have an extra “auto-start” setting; enable it for Lock.
• I locked myself out of something I needed. Use an emergency unlock, then remove that app from the list. That’s what the unlocks are for.
• I lost the tag. Wait for the auto-unlock, or use an emergency unlock, then pair a spare. Sticker packs come in tens for a reason.
• NFC isn’t detected at all. Check that NFC is on in Settings, and that your case isn’t metal or a wallet case with cards inside (they interfere).

What to expect the first week

Day one feels theatrical. You’ll hit the lock screen ten times and stand there. By day three you stop reaching. Not through effort: the reach just stops paying off, and the habit quietly loses interest.

That’s the point of the whole thing. You’re not managing screen time. You’re removing the decision from the moments where you’d lose it, and making it once, on purpose, with a tap.

If something isn’t clear or doesn’t work on your phone, the support page has the full FAQ and my email. I answer everything myself.