Know if your door is locked anytime, anywhere.
The UK's only retrofit Matter lock sensor
Monitor your door's lock state and whether it's open or closed — in a single Matter device that works with Apple Home, Google Home, Alexa, SmartThings and Home Assistant. No hub. No lock replacement. No app lock-in.
A Matter lock sensor that actually fits your existing lock
Until now, adding smart-home visibility to your door meant replacing the lock. Every Matter-compatible lock on the UK market — Yale Linus, Nuki, Bold, SwitchBot — is a full smart-lock replacement costing between £130 and £250. Matter door sensors from Eve, Aqara and Ring only detect whether the door is open or closed; they can't tell you whether the lock itself is engaged. The Locksure Matter Lock Sensor is the first UK-available device to solve both problems in one unit, on your existing lock, without a hub.
Works natively with every major Matter platform
Apple Home
via Matter
Google Home
via Matter
Amazon Alexa
via Matter
SmartThings
Samsung hub
Home Assistant
Any Matter integration
You'll need a Thread border router on your network — most homes already have one (Apple TV 4K Wi-Fi+Ethernet, HomePod mini, Nest Hub 2, Echo 4th gen, or eero 6+). Don't have one? A HomePod mini runs around £99 and serves a whole house.
Why nothing else on Matter does this
Smart-home shoppers searching for a Matter lock sensor have two options today: replace the lock entirely (expensive, not permitted for most tenants), or buy a contact sensor that only knows whether the door is open — not whether it's locked. Here's how we compare.
| Capability | Locksure Matter |
Yale / Nuki / Bold |
Eve / Aqara / Ring |
|---|---|---|---|
| Knows if lock is engaged | ✓ Yes | ✓ Yes | ✗ No |
| Knows if door is open / closed | ✓ Yes | Extra accessory | ✓ Yes |
| Works on your existing lock | ✓ Yes — retrofit | ✗ Replaces lock | N/A |
| Matter / Thread native | ✓ Yes | ✓ Yes | Varies by brand |
| Works with any Matter controller | ✓ Yes | Usually, yes | Usually, yes |
| Landlord / tenant friendly | ✓ Yes — adhesive | ✗ Lock swap needed | ✓ Yes |
| Price point (UK) | £79.99 / £99.99 | £130 – £250+ | £25 – £45 |
| Battery | CR2032, 2-year life, user-swappable | Rechargeable or AA (varies) | CR2032 / CR2450 |
Pricing and feature data for competitors verified April 2026. Contact sensors listed do not provide lock-state information; smart-lock replacements listed require removing the existing cylinder or thumb-turn.
One for each lock type
Locksure Matter sensors come in two variants, each designed for the lock you already have. Both ship with adhesive mounting, a reed-switch for door-position sensing, and a CR2032 battery pre-installed.
Thumb Turn MatterFor doors with an internal turn-knob
- Attaches over your existing thumb-turn with adhesive
- Magnetic hall-sensor detects lock rotation
- Reed switch senses door open / close position
- 2-year CR2032 battery, user-replaceable
- Matter over Thread — works out of the box
- Monitoring only — cannot remotely unlock (by design)
Key Turn MatterFor euro-cylinder locks turned with a key
- Fits standard euro-cylinder profile (30/30, 35/35, 40/40+)
- Adhesive mount, no drilling or key modification
- Detects key-turn events without reading the key itself
- Reed switch for door open / close
- 2-year CR2032 battery, user-replaceable
- Works with Apple Home, Google Home, Alexa, Home Assistant
The standard Locksure is available to buy today
If you don't have (or want) a Thread border router, our original hub-based Locksure uses its own display hub over Bluetooth — no Matter infrastructure needed. Same mechanical sensor design, same 2-year battery, available now at £69.99.
Takes about three minutes
Unlike a smart-lock replacement, there's no drilling, no removing the cylinder, and no locksmith visit. You'll use the Matter commissioning QR code that ships in the box — the same workflow as every Matter device.
Scan the Matter QR code
Open Apple Home, Google Home, Alexa, or your chosen app. Tap "Add accessory." Scan the code printed on the sensor.
Join the Thread mesh
Your Apple TV, HomePod mini, Nest Hub 2 or Echo 4th gen acts as the Thread border router. Commissioning happens automatically over Bluetooth LE.
Stick it to your lock
Peel the adhesive backing. Stick the sensor to your thumb-turn or euro cylinder. Stick the reed-switch magnet to the door frame. You're done.
For your existing lock
If you've been put off smart home products because you didn't want to replace your hardware or tie yourself to one ecosystem, Matter changes the maths — and the Locksure Matter sensor is built specifically to take advantage of it. Here's what's actually going on.
Matter is the shared language every major smart-home platform now speaks
Matter (formerly “Project CHIP”) is a wireless standard agreed between Apple, Google, Amazon, Samsung and the Connectivity Standards Alliance in 2022. Before Matter, a smart door sensor had to be built for one ecosystem — HomeKit, Google Assistant, Alexa, SmartThings — or it needed a manufacturer-specific hub to translate between them. That's why every smart home product bundle used to include a bridge. Matter eliminates that: one certified device works with every platform simultaneously. Apple Home and Google Home can both see the same sensor at the same time.
For a lock sensor in particular, this matters because lock state is one of the most safety-critical things in your home and you don't want it locked inside a walled garden. If you switch from an iPhone to a Pixel, your door sensor should still work. If your partner uses Alexa and you use Apple Home, you both want the same notifications. Matter is the first standard that actually delivers on that.
Thread is the wireless mesh Matter lock sensors use
Matter runs on two underlying radio protocols: Wi-Fi (for devices plugged into power, like smart speakers) and Thread (for battery-powered devices, like sensors). Locksure uses Thread because it's specifically designed for battery life — our sensor runs two years on a single CR2032 because Thread's radio uses roughly a tenth of the power Wi-Fi does.
Thread creates a mesh network inside your home. Each Thread device acts as a repeater for its neighbours, so the mesh gets stronger as you add more Thread devices. To connect the Thread mesh to your Wi-Fi network — and therefore to Apple Home, Google Home, or Alexa — you need something called a Thread border router. Most UK homes with any modern smart-home gear already have one.
Don't want to buy a Thread border router? Our original hub-based Locksure is available today at £69.99 and uses its own display hub over Bluetooth — no Matter, no smart-home platform required. Same mechanical sensor, same 2-year battery life. It's a simpler product for a simpler use-case: you just want to know if the door is locked, from your phone or the display hub on the wall.
Why a monitoring-only lock sensor is safer than a motorised one
Every Matter-compatible smart lock on the UK market — Yale Linus, Nuki Smart Lock, Bold Smart Cylinder — includes a motor. That motor is the feature people pay for: the ability to unlock your door remotely from your phone. It's also the feature that introduces every remote-attack vector that has been found in smart locks since 2015.
The Locksure Matter sensor is different: it exposes a Matter Door Lock endpoint in monitoring mode only. It reports whether the lock is engaged or disengaged, but physically cannot actuate the lock. There is no motor. There is no way for anyone on your Matter network — or on the Thread mesh, or for anyone who compromises your smart home hub — to unlock your door through our sensor. The only way to unlock your door is still with a physical key, from inside the house. This is a deliberate design choice.
This matters for PSTI compliance (the UK's Product Security and Telecommunications Infrastructure regime, which regulates all connected consumer products from 2024 onwards), it matters for home insurance (motorised smart locks are increasingly excluded from standard household policies), and it matters for tenants (whose landlords almost universally prohibit lock replacements).
How it looks in each platform
The same sensor, the same Matter commissioning, different apps. Here's exactly what shows up in each of the five major platforms and what you can do with it. Pick the one you actually use.
Apple Home iOS 16.1+
Appears as two tiles in the Home app: a Lock tile showing Locked or Unlocked, and a Contact Sensor tile showing Open or Closed. Both respond within about 2 seconds of the physical change. You can build Automations triggered by either state independently — for instance, “When the door is unlocked after 10pm, turn on the hallway light and send a notification to my iPhone.” Notifications respect your Home's people-at-home status, so the sensor doesn't bother you when you're the one unlocking the door. Works with Siri, with Focus modes, and with any Home-supporting HomePod speaker for announcements. Commission it once on any iPhone and it's shared across every device in your Home.
Google Home Android + iOS
The Google Home app shows the sensor in your home room layout with both Lock and Door entities. Google Home's automations are called Household Routines and can trigger on either state. Combined with Nest Hub, Nest Cam, or Nest Doorbell, you can build routines like “When the front door opens and it's after sunset, turn on the porch light and speak ‘Front door opened’ through the Nest Hub in the kitchen.” Google's Home & Away routines can also use the Door entity to decide whether the house is truly unoccupied. Alexa and Apple Home continue to work at the same time — there's no “commit to Google” trap.
Amazon Alexa UK + US skill
Alexa sees the sensor under Devices → Locks and Devices → Contact Sensors. You get voice status checks — “Alexa, is the front door locked?” and “Alexa, is the front door closed?” work out of the box, no skill enable needed. Alexa Routines can trigger on either state: “When the front door is unlocked, announce ‘Someone came in’ on the kitchen Echo.” Alexa Guard Plus (UK available since late 2024) can use the Door entity as a component of its “away mode” logic. A Thread border router is required — the Echo 4th gen, Echo Dot 5th gen, and eero mesh all qualify.
Samsung SmartThings requires Hub v3+
SmartThings Hub (v3 onwards, or the SmartThings Station) acts as both the Matter controller and the Thread border router. The sensor appears in the SmartThings app under the room you assign it to during commissioning, with both Lock Status and Contact Sensor endpoints exposed. SmartThings Routines are the most powerful automation engine of the five major platforms — you can chain Matter events with Zigbee, Z-Wave, and cloud services like IFTTT through a single routine. Particularly useful if you already have Samsung appliances or Galaxy SmartTags on the same SmartThings hub.
Home Assistant 2023.12+
Home Assistant has had native Matter support since version 2023.12 and is the most flexible of all five platforms for power users. The sensor exposes a lock.front_door entity (showing Locked / Unlocked state) and a binary_sensor.front_door_contact entity (showing open / closed). Both are independently scriptable in YAML or via the Automations UI. Several of our beta testers run Home Assistant as their primary controller and have built automations we wouldn't have thought of — for instance, “if the door is closed but the lock hasn't been engaged within 5 minutes, send a Pushover notification,” or “log every door state change to InfluxDB for a monthly audit.” Requires either a Home Assistant Yellow, a Home Assistant Green, a SkyConnect USB dongle, or any other Thread border router on the same network.
What people actually automate
Two independent states (lock engaged, door closed) unlock automation logic a single contact sensor can't do. Here are the six most common recipes from our beta testers — all of which work across every major Matter platform.
“Did I actually lock it?”
Trigger: Door closed for 3 minutes, lock still unlocked. Sends a gentle push notification — typically you're two streets away, still on foot, and it takes 30 seconds to turn back and lock it.
Heating off if door left open
Trigger: Door open for 2 minutes while heating is on. Turns the heating or the specific room's radiator off, turns it back on when the door closes. Surprisingly useful in autumn when people prop doors open for the dog.
Bedtime door check
Trigger: It's 11pm and the door is closed but unlocked. Sends a one-tap prompt to your iPhone or Android so you don't have to remember on your way upstairs. Stops firing if you've been in Do Not Disturb for longer than an hour.
Wandering alerts
Trigger: Door opens after midnight. Notifies a nominated family member's phone with the timestamp. Used by roughly a third of our beta testers looking after a parent with early-stage dementia — lower cost and lower privacy intrusion than a full telecare service.
Genuine “home unoccupied” logic
Trigger: Door closed and locked, no motion for 4 hours, our location says we're not home. Tells other smart devices (lights, heating, cameras) that the house is actually empty. Most automations use just GPS, which is brittle.
Slam alerts for teenagers
Trigger: Door state changes more than 4 times within 60 seconds. Sends a low-key notification so you can have the conversation without standing in the hall listening. Genuinely came up in user testing.
Common questions
Is this a Matter-certified product?
The Locksure Matter Lock Sensor is built on Nordic Semiconductor's CSA-certified Matter-over-Thread platform (Certificate ID: CSA25001MCPM0001-24). Our own full CSA product certification is in progress during May 2026. Early-bird units ship as Matter-compatible and will be eligible for the certified firmware update once our CSA audit completes.
Can it unlock my door remotely?
No — and this is intentional. The sensor exposes a Matter Door Lock endpoint in monitoring mode only. It reports whether the lock is engaged or disengaged but physically cannot actuate the lock. This keeps the product out of scope for remote-attack vectors that affect motorised smart locks, and means there is no physical pathway for someone to unlock your door through the Matter network.
Do I need a hub?
Not a Locksure hub, no. You do need a Thread border router on your home network — this is a standard requirement for any Matter-over-Thread device. Most UK smart homes already have one: the Apple TV 4K (Wi-Fi+Ethernet model), HomePod mini, Nest Hub 2nd gen, Nest Wifi Pro, Echo 4th gen, Echo Dot 5th gen, and eero 6+ all include Thread. If you don't have one, a HomePod mini starts around £99 and works for your whole home.
How is this different from an Eve Door & Window sensor or a Ring Contact Sensor?
A contact sensor (Eve, Aqara, Ring, SmartThings) tells you whether a door is open or closed — it detects magnet separation. It has no way of knowing whether your lock is actually engaged. You can close a door without locking it, and a contact sensor would still report "closed." The Locksure Matter sensor uses a magnetic hall-sensor on the lock body and a reed switch on the door frame, so it reports both states independently — in one device, on one Matter accessory.
Does it work with Home Assistant?
Yes. Home Assistant supports Matter commissioning natively from version 2023.12 onwards. The sensor exposes both a Door Lock entity and a Binary Sensor (door position) entity to Home Assistant. Several of our beta testers run Home Assistant as their primary controller and have built automations around both states independently — for example, alerting only when the door is closed but unlocked.
Will it fit my euro cylinder?
The Key Turn version fits standard British euro-cylinder profiles: 30/30, 35/35, 40/40, and asymmetric variants up to 50mm on one side. If you have an unusually ornate rosette or a heritage lock, measure the cylinder diameter before ordering — we have fitment diagrams on the Key Turn product page. The Thumb Turn version adheres to the inside face of the turn-knob itself and works on most European thumb-turn designs.
When does it ship?
Early-bird waitlist orders ship in May 2026 in the order they were reserved. General availability begins shortly after, at full RRP (£79.99 / £99.99). Reserving your sensor on the waitlist locks in the 30% early-bird price but doesn't charge anything until your unit is ready to dispatch.
Deeper guides on Matter lock sensing
If you want to understand exactly how this fits into your smart home, here are five in-depth guides we've written on the specifics — from the “Matter door sensor vs contact sensor” confusion to YAML automation for Home Assistant users.
Matter door sensor vs contact sensor: what's the difference?
The two types of product every “Matter door sensor” search returns — and which one you actually need.
Read → Apple HomeApple Home lock sensor UK: what actually works with HomeKit
Siri voice queries, Focus Modes, Thread border routers, and the UK options no-one explains upfront.
Read → Google HomeGoogle Home lock sensor UK: Matter with Nest and Household Routines
How the sensor surfaces in the Google Home app, what Routines you can build, and the Nest hub requirements.
Read → Home AssistantHome Assistant Matter lock sensor: the technical guide
SkyConnect and HA Yellow setup, entity structure, and four ready-to-paste YAML automation examples.
Read → Fitment guideRetrofit Matter sensor for euro cylinder locks: the UK guide
Sizing (30/30, 35/35, 40/40), tenant and insurance rules, and a three-minute install walkthrough.
Read →Reserve your Matter Lock Sensor
Join the waitlist. Lock in 30% off at launch. We'll email you once units are ready to dispatch — no charge until then.
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