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.
of burglaries happen through unlocked doors
Know your door is locked — anytime, anywhere.
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The Locksure Hub isn't required to use the Matter Lock Sensor — your sensors work standalone with Apple Home, Google Home, Amazon Alexa, SmartThings or Home Assistant. Add the Hub when you want door sharing across smart-home accounts, geofence "you left it unlocked" alerts, months of cloud-archived history, and an at-a-glance round touchscreen for the four most-important doors.
Learn what the Hub adds ↓Don't need Matter? The Original Locksure might be your best option.
Same hardware, proven firmware, 16 months in customer homes — and it works on its own with the Locksure app over Wi-Fi. If you're not on Apple Home, Google Home, Alexa, SmartThings or Home Assistant — or simply don't want a Thread border router — the Original Locksure is the simpler, no-ecosystem choice. Lock state, same Locksure app, same 2-year CR2032 battery, no Matter required. (Open/close door detection is currently Matter-only; coming to the Original Locksure in a future firmware update — all sensors already have the required hardware.)
A Matter lock sensor that actually fits your existing lock
Until now, adding smart-home visibility to your door meant one of two compromises. Either a full smart lock — Yale Linus, Nuki, Bold and similar all swap the cylinder out at £150–£425 and usually a locksmith fit, or the Aqara U200 retrofit at £128 which mounts over the thumb-turn but motorises it (Li-ion recharge every ~6 months, remote-unlock attack surface, no contact-sensor endpoint). Or you settle for a contact sensor from Eve, Aqara or Ring that only knows whether the door is open, not whether it's locked. The Locksure Matter Lock Sensor is the first UK-available device that reports both lock state AND open/close from one Matter unit, sits on top of your existing lock without motorising it, and ships at £55.99 early bird.
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 we built it this way
Locksure isn't trying to be a smart lock. We deliberately chose not to put a motor on your door. The category we built for is people who want lock-state visibility without a motorised actuator — and that's a much larger group than the smart-lock conversation usually credits.
Most UK rental agreements don't allow cylinder replacement. Locksure sits on the existing lock with 3M VHB — the cylinder is untouched, so you stay compliant with the agreement.
Modern uPVC front doors use multi-point lock systems that no actuating smart lock can physically drive. Locksure detects thumb-turn rotation only, so it works on every UK euro-cylinder door regardless of mechanism.
An adult child sees a parent's doors live, without taking control or surveilling them. The companion app's door-sharing feature gives read-only visibility — no remote unlock, no privacy creep.
A typical UK locksmith call-out to fit a smart lock runs £100–150 on top of the device itself. Locksure self-installs in five minutes with 3M VHB — no drill, no screws, no callout fee.
Some UK home insurance policies require specific cylinder profiles or prohibit motorised locks. Locksure adds smart-home visibility without changing what's already approved.
A motorised lock is an attack surface. Locksure physically cannot unlock your door — no motor, no actuator. The worst case in a fabric compromise is that someone sees your lock state.
If you want a full smart lock that locks and unlocks remotely, we don't compete with the Aqara U200 Lite at £128, Yale Linus or Nuki — those are good products for a different problem. We're a different category, and the buyer above is who we built for.
Where Locksure sits in the UK Matter market
Three honest categories. Smart locks that actuate your door are powerful but expensive and usually need a locksmith. Contact sensors are cheap but only know whether the door is open. Locksure is a middle-ground category — lock-state monitoring without the actuator.
| Capability | Locksure Matter | Full Smart Locks Yale Linus · Nuki · Bold | Matter Contact Sensors Eve · Aqara P3 · Ring |
|---|---|---|---|
| Knows if lock is engaged | ✓Yes | ✓Yes (by actuating it) | ✗No |
| Knows if door is open / closed | ✓Yes (built-in) | Extra accessory | ✓Yes |
| Both endpoints on one Matter device | ✓Unique | ✗No | ✗No |
| Works with your existing lock | ✓Yes (sits on door face) | Mounts over thumb-turn (Bold replaces cylinder) | ✓Yes |
| Tenant-friendly install | ✓Yes (3M VHB, removable) | Removable mount (heavier hardware) | ✓Yes |
| Self-install time | 5 min | 15–30 min DIY (Bold needs locksmith) | 5 min |
| Battery life | CR2032 · 2 yr | Li-ion · ~6 mo recharge | Coin cell · 1–2 yr |
| Multi-point UK door | ✓Yes | ✗Cannot drive multi-point | ✓Yes |
| Cannot be exploited to unlock | ✓By design | ✗Remote-unlock surface | ✓N/A |
| UK price (device only) | £55.99 early bird · RRP £79.99 | £128 – £425 (+ install) | £25 – £55 |
UK retail prices as listed May 2026. The Aqara U200 is a retrofit that mounts over the existing thumb-turn (DIY install, similar style to Locksure but motorised); Yale Linus, Nuki and Bold are cylinder-replacement smart locks and typically need a locksmith. Page corrected 30 May 2026 after community feedback.
Specifications, up front
TECHNICAL_SPECIFICATIONS_V2.0
Native Matter; no proprietary bridge. Direct IP routing on the Thread mesh.
12 G Bop / 4 G Brp. Polled at >100 Hz. No contact wear.
FCC, CE, UKCA, IC & MIC certified silicon. BLE 5.3 + 802.15.4 / Thread.
System-OFF deep sleep at 4.6 µA idle floor. Reported per event in-app.
Set per-door in the app. Starts high for reliability — app shows live Thread signal strength and recommends a lower level once attached, so you can trade range for battery life.
Two Matter device-type endpoints on one physical product — Door Lock plus Contact Sensor.
Survives reboot & phone-handoff. Back-fills on next connect.
Hold the button 5–10 s (solid magenta) to arm BLE DFU; 10 s+ (solid blue) triggers factory reset. Signed MCUboot, per-customer rollout, SHA-256 + MD5 + size verified pre-install.
3M VHB. Tenant-friendly. Fits euro-cylinder thumb-turn or key-turn UK locks.
Encrypted at the Matter session layer (AES-128-CCM). No internet account on the device itself.
Matter, on hardware that's been in homes for 16 months
The Locksure Monitor isn't a prototype. The same physical hardware has been in customer homes since January 2025 — battery chemistry, sensing, mechanical fit, OTA pipeline, button-press handling, real-world thermal range — all already proven across real installs and live for over a year. What's new is the Matter firmware layer running on top of that proven base. The six-month log below covers exactly that software work — the hardware was already a known quantity going in.
MATTER_BUILD_LOG // DEC_2025 → JUN_2026
Matter firmware bring-up
Existing field-proven hardware booted into a fresh Matter-over-Thread firmware image. Two Matter endpoints (Door Lock + Contact Sensor) wired up on a single MCU — a configuration no other UK retrofit product ships.
Pairing & spec compliance
Stabilised the Matter pairing flow across Apple Home and Google Home. Two-endpoint compliance work — both endpoints announce, hold subscriptions and survive a Thread mesh re-route. Setup-code provisioning automated end-to-end through the Locksure app so the user never has to scan a QR code.
Power budget under Matter
The hardware was already a 2-year-battery design under the legacy firmware. Re-validated the power budget under the new Matter image on bench instrumentation — the floor held, even with the Thread radio added to the picture.
Apple + Google fabric tests
Multi-admin commissioning verified across Apple Home (HomePod mini and Apple TV 4K as Thread border routers), Google Home (Nest Hub Max and Google TV Streamer 4K), SmartThings (Samsung hub) and Home Assistant (SkyConnect dongle). All four fabrics holding subscriptions on the same device — lock and contact state observed live on every controller.
App commissioning
The Locksure app commissions Locksure devices directly — using the iOS HomeKit Matter handoff on Apple, and the standard Matter SDK commissioning flow on Android. Hub-side subscription path validated end-to-end on every fabric, including the awkward case where only Apple Home is set up first.
Hub, sharing, OTA, production-readiness pass
Hub archiving events to long-term cloud storage with authenticated credentials. Door-sharing behaviour finalised — Hub becomes sole writer of rooms.state for shared doors so shared and owner views always agree, regardless of which smart-home platform either is on. Per-customer staged OTA rollout with size + SHA-256 + MD5 verified pre-install. Background geofence shipped on iOS with a clear "Always" location disclosure. Final production-readiness test pass on real hardware (RIG LSM + MatterHub, iOS 26.5) — every user-guide workflow verified end-to-end.
PUBLIC_LAUNCH · shipping today
Early-bird units shipping to UK customers at £55.99. App live on TestFlight / App Store, Hub firmware production build (REMOTE_DEBUG compiled out), LSM Matter firmware v68 deployed via signed-OTA pipeline. r/MatterProtocol + r/HomeAssistant launch coverage live. Locksure Hub is optional — sensors work on any Matter controller (Apple Home, Google Home, SmartThings, HA) standalone.
Android feature parity
Every feature shown on this page — heatmaps, sharing, geofence, history, Hub controls, OTA from the app — lands on Android. Same backend, same Matter commissioning flow, same Hub-side behaviour. iOS leads launch by a few weeks; Android closes the gap.
CSA cert + free OTA to certified firmware
Full CSA Matter product certification completes — at which point every shipped device receives a free signed OTA with the production Vendor ID and the "Uncertified Accessory" warning goes away on Apple Home. Detector reliability improvements (consecutive-poll filter) ride the same OTA wave for any units flagged in field telemetry.
Got a technical question — Thread mesh sizing, fabric handling, app architecture, OTA pipeline? We answer them within 24 h.
Ask a question →An app that actually adds something beyond your Apple Home tile
Apple Home and Google Home show you a single state right now. The Locksure app keeps a long-term history, lets you spot patterns, share doors with family, set up geofence alerts, and see who came and went across all your doors at a glance — features that Matter alone doesn't expose.
ANDROID_PARITY · MID_JUNE_2026 Every feature on this page ships to Android in mid-June 2026 — same Locksure app, same Matter commissioning flow, same Hub features, same heatmaps and pattern insights. iOS leads launch by a few weeks only.
Full event history
Every lock, unlock, open and close. The Monitor stores the last 64 events on-device by default; with a Locksure Hub paired, every event is archived to the cloud — months of searchable history.
Activity heatmaps
Per-door and all-doors 7×24 heatmaps over the last 30 days. Spot "front door is mornings, back door is evenings" in one glance.
Door sharing
Share any door with a family member by email. They get live state updates and history on their phone — independent of which smart-home platform they use. Revoke anytime. Requires a Locksure Hub.
Left-home geofence alerts
Get a push the moment you leave home with a door still unlocked. Tunable radius. Works while the app is closed; battery-efficient. Requires a Locksure Hub.
Pattern insights
Per-door peak time, busiest day, weekday/weekend split, time-of-day band, daily average. Surfaces things you'd otherwise never notice.
Temperature & battery
The device reports its own internal temperature and battery level on every event.
Over-the-air updates
New firmware ships to the Locksure Monitor directly from the app — no taking the cover off, no USB cables. Per-customer rollout for safety; checksum-verified.
Reliable across users
Owner and shared users see the same live state on their tiles. Notifications are debounced and deduplicated so you never see the same event twice.
Nicknames for shared owners
When somebody shares a door with you, give them a nickname (mum, dad, landlord). It auto-applies across every door they share with you.
APP_SCREENS // LIVE_REFERENCE
SYNCED_FROM_HUB Screenshots taken from a live install, 4 doors, mixed states
All your doors with current state, last event time, low-battery warning and Matter live indicator.
A second person — here on Android — sees the doors mum shared. Nickname plus email below.
7×24 grid per door over 30 days. Each door has its own colour and own quieter→busier scale.
Day, hour range, door name and event count pin at the top — tap again to dismiss.
Daily-average, weekday %, dominant time-of-day band, busiest and quietest doors, per-door peak slot.
Anyone with a Locksure account. Recent recipients suggested as chips. Revoke any time.
Anyone you've previously shared with appears as a chip — with the nickname you've given them.
Battery, last operation, temperature, firmware version + update button, activity heatmap shortcut.
Brightness, flash-when-unlocked, ALL GOOD indicator, doors-on-this-hub. Inline — no separate hub app.
Transparent disclosure of exactly what background location is used for. No tracking, no sharing.
Auto-detects from current GPS. Default 100 m radius — adjustable.
One screen. Notifications, history, geofence, account. Hub options live inline next to each door.
Built so you never miss an event
The sensor runs a private vendor cluster alongside the standard Matter Door Lock cluster. That means it keeps a 64-event ring buffer locally on the device. When your phone reconnects (or another household phone reconnects), it back-fills any events missed while everyone was out of range. You don't lose state because somebody's phone was in airplane mode.
64-event on-device buffer
Survives reboots and platform-handoff. Back-filled when the next phone connects.
Server-side dedup
Same physical event arriving via live Matter and via history sync collapses to one notification.
Anchored timestamps
Boot-epoch anchor means every event has the same wall-clock time on every device.
Pick the kit that matches your door
Two starter packs, one of which suits every UK euro-cylinder front, back or garage door.
Thumb Turn Monitor (TTM)
Single Locksure Monitor that sits on the inside of the door and senses the thumb-turn rotation. Detects key turns from either side via the same magnet pattern. Best for most UK doors.
Key Turn Monitor (KTM)
Two Locksure Monitors — one each side of the door. Whichever side last moved sets the displayed state. Required for keyed-both-sides locks (no thumb turn). Common on listed-building front doors and rentals.
Add-on Open / Close (OC) Magnet
Sensor already on the Locksure Monitor + magnet that ships with both starter packs. Sticks to the door + door frame. Reports the second Matter endpoint (Contact Sensor).
Five minutes from box to live tile
The setup is the same for every Matter platform. Pair once in Apple Home, Google Home, SmartThings or Home Assistant — then the Locksure app picks the device up and adds history, sharing, geofence and heatmaps on top.
Tap "+" then "Lock Sensor". The app guides you through every step.
Locksure Monitor ready, Apple Home (or Google etc.) installed, Thread border router on the network.
Thumb Turn or Key Turn. Locksure pre-fills the room name so it shows correctly in Apple/Google Home.
Pairing starts the moment a battery goes in. Only have one un-paired Locksure Monitor with battery in at a time.
"Add Anyway" is safe. The name doesn't matter. The room doesn't matter — Locksure overrides both.
Apple's standard sheet appears. Tap "Add to Home" — Locksure passes the setup code automatically.
During CSA certification we use a test vendor ID. The radio + crypto stack is Nordic-certified. Safe — see below.
Ignore the name field, ignore the room — Locksure renames the device to your real door name as soon as pairing finishes.
Apple Home shows the device as a Lock plus a Contact Sensor — the unique Locksure dual-endpoint setup.
Apple Home returns you to Locksure. Tile, history, sharing — all populated within seconds.
The 4 doors appear on Apple Home's Security tab as tiles — locked = dark / padlock, unlocked = highlighted. The small door-shape icon on the Activity row ("2 Doors Unlocked") is Apple's visual for the open/close contact-sensor endpoint that the Locksure Monitor also publishes — proof that the device is exposing both Matter endpoints (Door Lock + Contact Sensor) as one accessory, which no competitor on Matter does today.
A real automation built on the Locksure Monitor's contact sensor: "When Back Door Opens → Turn On Light". Because the device publishes a standard Matter Contact Sensor endpoint, every Apple Home / Google Home / SmartThings / Home Assistant automation engine treats it as a first-class trigger. No vendor app, no integration glue.
About the "Uncertified Accessory" warning
It looks alarming but it isn't. The warning appears because we use a test Vendor ID during CSA certification — full product certification is in progress and lands as a free signed OTA when complete. Here's what's actually under the case:
Nordic Semiconductor nRF52840
FCC, CE, UKCA, IC and MIC certified silicon. The Bluetooth, Thread and Matter stacks are Nordic's CSA-audited production code.
Matter spec compliant
Implements the standard DoorLock cluster (0x0101) and BooleanState (Contact Sensor) on a second endpoint exactly as the Matter specification defines them.
End-to-end encrypted
Matter session keys are negotiated per fabric. There is no internet account on the device itself. The Locksure cloud only receives data the customer has shared.
UK manufacturing
Designed and assembled in Glasgow. RoHS compliant. The plastic is mineral-filled and recyclable.
From box to live tile, step by step
Every workflow below has been verified end-to-end against real hardware (RIG LSM + MatterHub, iOS 26.5) during our production-readiness pass. If a step says "verified", we ran it and watched it work from the app through the lock and hub all the way into Firestore.
APP_WORKFLOWS // FIRST_5_MINUTES → LIFECYCLE
1. Create your account ~1 minute · empty inbox to clean slate
- Open Locksure → Sign up.
- Enter email + password.
- Allow notifications when prompted — needed for lock/unlock push alerts. (Tapped "Don't Allow" by mistake? Re-enable in iOS Settings → Locksure → Notifications.)
Verified: user doc created, FCM token registered, clean slate (0 rooms / 0 devices / 0 hubs).
2. Add your first lock — no hub required app-only setup works on any Matter controller
A Locksure lock works app-only — your iPhone reads its state directly through Apple Home, no Locksure Hub needed. The hub is optional and adds always-on mirroring + shared-user support.
- Home screen → tap + (Add Device).
- Choose the lock / door-monitor type.
- When asked "Add to a hub?" — tap Don't add to a hub for app-only.
- Apple's "Add Accessory" sheet appears. Scan the QR code on the lock, or it may auto-detect over Bluetooth. If it shows "Uncertified Accessory", tap Add Anyway.
- Give the door a name (e.g. Front, Rig). This name flows through to the Locksure app, Apple Home and the hub display if you add one later.
Verified: lock commissioned in ~35 s, live lock + door + battery state surfaced in the app within ~2 s of pairing completion.
3. Reading your lock's state tile colours + Matter event codes
The Home-screen tile reflects the door's current state in colour:
- Locked — deadbolt thrown (Matter event 1)
- Unlocked — deadbolt open (Matter event 2)
- Open — door physically open (Matter event 3)
- Closed — door shut, shown using unlocked styling (Matter event 4)
Battery percentage and Matter signal strength appear on the tile. Turning the key or opening/closing the door updates the tile within ~1–3 seconds while your iPhone is nearby and the app is open.
Verified: live lock (1=Locked / 2=Unlocked) and door (3=Open / 4=Closed) events updated rooms.state and the tile in real time, app-only, no hub.
4. Add a hub (optional) always-on mirroring + sharing
The Locksure MatterHub is optional. Add one if you want:
- Always-on state mirroring — your door's state stays current in the app even when your iPhone is away or the app is closed.
- Shared-user access — share a door with another Locksure account; they see live state without needing to be on your Apple Home.
- Long-term history — months of searchable events archived to your account.
- At-a-glance touchscreen — up to 4 doors visible on the hub's circular display.
Steps
- Home screen → + → choose to add a hub (or, when adding a lock, choose Add to a hub).
- The hub pairs in two stages: first it joins your Wi-Fi over Bluetooth, then it commissions onto Matter. Keep the app open and stay nearby for both.
- Once paired, the hub appears and automatically picks up the locks you've already added, mapping each to a door slot.
Verified: hub commissioned in ~33 s, auto-mapped the lock to door 0, connected to Wi-Fi, subscribed to the lock, and began writing room state to the cloud (state, last-update time, hub IP all refreshed live).
Once paired, the hub becomes the source of truth for any shared door's tile — the app steps back so shared users and the owner always see the same state, even with the owner's app closed.
5. Share a door live state + history for a second account
- Open the door → Share → enter the other person's Locksure account email.
- They get access immediately — the door appears on their Home screen with live state.
For live sharing, the door should be on a hub. Without a hub, a shared user can still be granted access, but their live state depends on the owner's app being open and nearby.
Verified: sharing a door to a second account added them to the shared list; the hub immediately took over as sole publisher of the door's state; the second account saw live lock/unlock updates and the door's history.
6. Add a second lock to an existing hub expand the household
- App → Add Device → choose Lock.
- Insert the battery in the lock you want to pair (or power-cycle it). Only one new lock at a time — see Troubleshooting if pairing fails.
- When pairing completes, the app asks "Add to existing hub?" — tap Yes and pick your hub from the list. The picker shows each hub's currently-assigned locks so you know where the new one is going.
- The hub picks up the new lock within a second or two — its door tile appears on the hub display with the name you gave during pairing.
Verified: two-lock-on-one-hub setup. Both locks reported state through the hub and showed on its display with correct names.
Heads-up: in the current factory firmware, two unpaired locks advertise with the same Bluetooth ID. When you pair a second one, only power up the lock you're adding (battery out on any others), then power them all back up once the new lock has paired.
7. Remove a lock from a hub (keep it as app-only) hub stops mirroring, app still works
- Open the door tile → Hub section → tap the lock under "Locks on this hub" → Remove from hub.
- The hub's display tile for that lock disappears within a couple of seconds.
- The lock keeps working in the app — only the hub mirror is gone.
Verified: removing a lock from the hub clears the hub's display tile and door count immediately; the lock continues to work as an app-only device.
8. Remove a lock entirely full cleanup across app, Apple Home and hub
- Open the door tile → ⋮ menu → Delete.
- Confirm. The lock disappears from your home screen, from Apple Home, from the hub display, and any shared users lose access.
If this was the last lock on a hub, the hub also factory-resets itself automatically — it goes back to setup mode and disappears from Apple Home. An empty hub serves no purpose, so we tidy it up for you.
Verified: deleting a hub-monitored, shared lock cleared the lock from Apple Home, the hub display, every Firestore record, and the shared user's home screen — and the hub returned to setup mode automatically.
9. Remove a hub (keep your locks) no touchscreen factory-reset needed
- Home screen → tap the hub section to expand → scroll to Remove Hub → confirm.
- The hub factory-resets itself (Wi-Fi + Matter cleared) and returns to setup mode — ready to be re-added later or set up on a different account.
- Your locks stay paired in the app as app-only devices.
Verified: Remove Hub cleared the hub's Wi-Fi + Matter state, the hub rebooted into BLE setup mode, and Apple Home evicted the hub accessory within a poll cycle. Re-adding the hub via Add Hub goes through the normal flow (Wi-Fi auto-fills from your saved network).
HARDWARE_REFERENCE // LEDS_BUTTONS_DFU_FACTORY_RESET
LED cues at a glance
The two SMD LEDs face the front of the Locksure Monitor. Both LEDs flash together (System ON mode) or sequentially (System OFF, half the peak current). Same cues regardless of which mode you're in.
Amber flash · LOCK~80 ms, both LEDs together
Cyan flash · UNLOCK~80 ms, both LEDs together
Green flash · CLOSEOC magnet reports door closed
Blue flash · OPENOC magnet reports door open
Blue · PAIRING (left then right)Matter / BLE commissioning — firmware lights LED1 then LED2 in turn
Blue · DFU PENDING (left→right sweep)You've tapped Update firmware in the app. The Monitor sweeps blue for ~1.8 s as confirmation, then reboots into the BLE-DFU loader to receive the new image.
Magenta · SETTING SAVED (both)Both LEDs flash magenta together when a new setting (TX power, etc.) arrives from the app — visual confirmation the device received and applied it.
Button-hold cues: solid magenta at 5–10 s (release for BLE DFU), solid blue at 10 s+ (release for factory reset). The factory-reset sweep is covered separately below.
The 4 short-press settings cycle 1→2→3→4→1 each press
One short press of the button cycles through the four installation orientations. The device shows you the colour + side that matches your new setting, then reboots. The setting is preserved across battery removal.
| Setting | LED | Side | Direction | Use when |
|---|---|---|---|---|
| 1 | West | Normal | Most UK thumb-turn doors. Locksure Monitor right of the thumb-turn looking from inside. | |
| 2 | East | Normal | Locksure Monitor left of the thumb-turn looking from inside. | |
| 3 | West | Inverted | Lock turns the opposite way from default — e.g. some euro cylinders with the cam pointing up. | |
| 4 | East | Inverted | Mirror of setting 3. |
Key Turn vs Thumb Turn — which do I have? decides whether you need 1 or 2 Locksure Monitors
Thumb Turn (TTM)
Look at the inside of your door. Is there a thumb-grip you can twist by hand to lock/unlock? Then you have a thumb turn. One Locksure Monitor suffices. It senses the turn and tells you the state — whether the key turned the lock from outside, or your hand did from inside.
Key Turn (KTM)
If the inside is a keyhole — no thumb-grip — you have a key-turn lock. You need two Locksure Monitors. Each side detects its own key, and whichever side last moved sets the displayed state.
TX power levels (1–5) balance range vs battery life
Lower power saves battery; higher power gives more range. Adjust from the per-door bottom-sheet in the app. Defaults to level 2. The change takes effect on the next event — no reboot needed.
| Level | TX dBm | Approx range | Battery impact |
|---|---|---|---|
| 1 | 0 dBm | ~5 m, line-of-sight | Best — lowest current draw on TX bursts |
| 2 (default) | +2 dBm | ~8 m | Very good — chosen for typical UK homes |
| 3 | +4 dBm | ~15 m | Good — balanced |
| 4 | +6 dBm | ~22 m through one wall | Average |
| 5 | +8 dBm | ~30 m, two walls | Heaviest — only use if range is genuinely a problem |
DFU (firmware update) mode over-the-air updates from the app
DFU runs in a separate firmware-loader image — the main Matter app reboots into it so BLE DFU can't clash with the live Matter session. Throughout DFU the device shows yellow (red + green LEDs together), deliberately distinct from the blue commissioning indicator so you can tell the two modes apart at a glance.
Trigger DFU from the app
Open the door's bottom-sheet, tap "Update firmware to vX" if shown. The app sets the boot-mode flag and the Locksure Monitor reboots into the firmware-loader. (No LED activity while the main app is still running.)
Yellow heartbeat — advertising for connection
Loader is up and advertising as LocksureDoor-DFU over BLE. Both LEDs blink yellow together for 30 ms every 3 s — a quiet "I'm alive, waiting" pulse. The Hub / app will connect within a few seconds.
Rapid yellow during transfer
Once the Hub connects, each BLE chunk arriving (one every ~5 ms) triggers a 10 ms yellow flash — the device appears to flicker yellow continuously while data is streaming. Don't power-cycle. Stay within BLE range. Total transfer is ~35–50 s for a typical Matter Monitor firmware image.
Completion flash + silent reboot
When the END marker arrives the loader fires one final 100 ms yellow flash, then reboots. MCUboot verifies the new image's signature on cold boot — if valid the device boots the new firmware; if invalid it reverts to the previous image. There's no LED cue for verify-pass / verify-fail — both end with the device coming up normally (just with a different firmware version visible in the app).
Stuck DFU? The loader has a 120-second stall watchdog: if no BLE activity is seen for that long, the device automatically reboots back to the normal Matter image. You won't get stranded.
Factory reset two paths · the recommended one is automatic
There are two ways to factory-reset a Locksure Monitor. The first is automatic and almost always the right one. The second is a manual button-hold for the case where the device is offline or already removed from its smart-home fabric.
Method 1 — remove from Apple Home / Google Home (recommended)
When the smart-home app sends the standard Matter "remove fabric" command, the Locksure Monitor sees it and auto-resets ~1.5 s later. No physical access needed.
Delete the accessory in Apple Home / Google Home
This sends the Matter RemoveFabric command. The device's OnFabricRemoved handler schedules a factory reset 1500 ms later.
Device wipes NVS and reboots into commissioning mode
Button setting, TX power, all paired fabrics — gone. The device boots back up as if fresh from the factory.
Re-pair from the Locksure app
Tap "+" → "Lock Sensor" and follow the normal pairing flow. The device is in BLE-advertising mode for ~3 min after reboot.
Method 2 — manual button hold (fallback)
Use this if Method 1 doesn't work (device offline, never received the RemoveFabric command, or you've lost access to the original smart-home account). The LED colour while you hold tells you which mode you're about to enter on release.
Press and hold the button
Keep your finger on it. The LEDs will show different colours as you cross each timing threshold below — don't release until you see blue.
~1 s — orange preview (medium press)
Releasing now would cycle the TX power level. Keep holding past this.
~10 s — magenta both LEDs (long press = DFU)
Releasing here would reboot into the BLE DFU firmware loader. Keep holding to reach factory reset.
~20 s — blue both LEDs (very long press = factory reset)
You can release now. The device fires six confirmation flashes, wipes NVS, and reboots.
Device reboots into commissioning mode
Same end-state as Method 1. Re-pair from the Locksure app.
Note on Method 2: the LED preview while holding is unambiguous — orange = "you've crossed 1 s", magenta = "you've crossed 10 s, releasing now triggers DFU", blue = "you've crossed 20 s, releasing now triggers factory reset". If you panic and release during magenta the device will reboot into the BLE DFU loader instead of factory-resetting — pull the battery and try again.
Remove a Locksure Monitor from the app delete the door tile
On the home screen, tap the red delete button on the door's tile. Confirm in the dialog. The room is restored if there were other Locksure Monitors on it (e.g. removing one side of a KTM); fully deleted if it was the only Locksure Monitor. Important: always remove the device from Apple Home / Google Home as well before re-pairing.
When you want a physical display
The Locksure Hub is the gateway that unlocks the premium app features: door sharing (invite a family member by email — any sharing requires the Hub), geofence alerts ("did I leave a door unlocked when I left home?"), and long-term event history (months instead of the device's on-board 64-event ring). It also adds a permanent at-a-glance display — a 32 mm round touchscreen mounted to USB-C power, showing up to 4 doors. The screen is a capacitive touchscreen: tap to enter setup mode, long-press to factory-reset the Hub, double-tap to flip the display orientation (useful when the Hub is wall-mounted upside-down).
4-door quadrant view · mixed states
FRONT locked (blue) · BACK unlocked (amber) · PATIO open (red) · GARAGE locked (blue)
ALL GOOD
Shown when every door is locked. Blue ring + lock icon · NOT green (the firmware uses blue for the locked/all-good state).
Setup mode · tap screen to enter
Purple home + Bluetooth · SETUP, grey instruction. A single tap on the touchscreen puts the Hub here; from here it advertises BLE and the Locksure app picks it up.
Firmware update
"UPDATING" + percentage + KB/s rate. Ring fills counter-clockwise as the update transfers.
What the Hub adds
Required for door sharing
Invite a family member by email to monitor any door. The Hub mediates the share so the recipient sees live state and history regardless of which smart-home platform they use.
Geofence alerts
"Door left unlocked when I left home" push notifications need the Hub to keep door state live in the background, even with the app closed.
Long-term history
Without a Hub, the Monitor's on-board ring holds 64 events. With a Hub, every event is archived to Firestore — months of history with full search.
At-a-glance touchscreen
Mount on a hall console. See every door's state with no phone unlock, no app open — and reach for it with your finger when you do need to act on it.
ALL GOOD indicator
Single blue ring + big lock icon + "ALL GOOD" the moment every door is locked. One glance before bed instead of opening four tiles.
Touch controls on the Hub
Three gestures, no buttons. Tap to enter setup mode (when you need to add the Hub to a new WiFi, or pair a new Monitor to it). Long-press to factory-reset the Hub. Double-tap to flip the display orientation — handy if the Hub ends up wall-mounted upside-down or you want to rotate it 180° on a shelf.
If something isn't behaving
Every fix below was verified end-to-end during the production-readiness pass. Grouped by where the problem shows up — pairing a lock, pairing a hub, day-to-day operation. Most issues resolve in under 60 seconds.
PAIRING_A_LOCK
"0 devices found" during the scan most common first-attempt issue
The lock only advertises over Bluetooth while in setup mode. Work through these in order:
- Toggle iPhone Bluetooth off, then on (Settings → Bluetooth). This clears the iOS Bluetooth scan cache and is the single most effective fix.
- Power-cycle the lock (remove battery, reinsert). This restarts its ~15-minute Bluetooth advertising window. Commission within a couple of minutes of powering it back on.
- Stand within ~1–2 m of the lock during the scan — weak signal causes intermittent discovery.
"Pairing Failed" / commissioning aborts partway stuck Apple Home state — restart the iPhone
- Only have ONE new lock in setup mode at a time. Two un-commissioned locks advertising at the same time can collide during pairing. Power down any others, add one lock, then add the next.
- Restart your iPhone. After several add/remove attempts, Apple Home's internal pairing state can get into a stuck condition that makes every new attempt fail — often quickly, within ~15–20 s. This is the highest-value step after repeated failures — do it before trying many more times.
- Power-cycle the lock after a failed attempt before retrying. A failed pairing can leave the lock briefly "busy" (internal safety timer) for up to a minute; a power-cycle clears it.
- Wait for the iPhone to fully boot and the lock to be freshly powered, then make one clean attempt rather than many rapid ones.
Tell-tale of "stuck Apple Home": attempts that fail quickly (15–20 s) after several earlier attempts, often with no pairing-sheet progress. That quick-fail pattern = restart the iPhone.
Verified recovery sequence (when nothing else works) ~15 failures → commissioned in 35 s
This exact sequence reliably recovered a stuck pairing during testing after ~15 failed attempts. Use it as a last resort:
- Power down all but the one lock you're adding.
- Restart the iPhone.
- Power-cycle that one lock.
- Wait for the iPhone to finish booting, reopen Locksure, then Add Device — one attempt. Commissioned in ~35 s.
"Uncertified Accessory" warning on Apple Home expected — tap Add Anyway
Tap Add Anyway. We use a test Vendor ID until full CSA product certification completes. The hardware is Nordic-certified — FCC, CE, UKCA, IC and MIC compliant — and the Bluetooth/Thread/Matter stacks are Nordic's CSA-audited production code. Once CSA cert lands, certified firmware reaches every shipped device as a free signed OTA and the warning goes away.
Door tile says "Locked" but the door is actually unlocked orientation setting needs inverting
Press the Locksure Monitor's button once — the LED will flash, indicating you've moved to the next of four orientation settings. Keep pressing until the lock direction matches reality (settings 1→2→3→4→1 cycle). The colour tells you which mode you're in: cyan = normal, amber = inverted; right LED = West-side install, left LED = East-side install. See the LED-cues + 4-setting table in the User Guide for the full mapping.
PAIRING_A_HUB
"Add Hub" shows no Wi-Fi networks (empty list) hub-side scan over BLE
The hub scans Wi-Fi over Bluetooth during setup. If the list is empty:
- Tap Rescan — it triggers a fresh hub-side scan rather than re-reading a cached list. The button is present whether networks were found or not.
- If still empty, hold your phone within ~1 m of the hub during the scan (Bluetooth signal must stay strong while the hub tears down BLE briefly to run the Wi-Fi scan).
- Last resort: power-cycle the hub (unplug, wait 5 s, plug back in) and restart the Add Hub flow.
Hub didn't pick up a newly-added lock re-push door mappings from the app
- After pairing finishes, give it ~5 s — the hub picks up the new lock silently in the background.
- If the new lock still doesn't appear on the hub display after 30 s, open the door tile → Hub section → tap Push door mappings to hub. That re-pushes every assigned room/door to the hub from your phone.
- If you only see one lock when you expected two, both unpaired locks may be advertising at the same Bluetooth ID (factory firmware quirk). Power down all but one, retry.
Hub display shows the wrong door name re-sync from the app
The door's name on the hub display is whatever you typed during the wizard; the lock's name is set when you add the lock. These can drift apart. To re-sync:
- Open the door tile → Hub section → tap Push door mappings to hub. This rewrites the hub-side display name to match what's in the app.
Hub still shows a door you just removed briefly normal · power-cycle if it persists
For a fraction of a second the door tile may linger on the hub screen while the hub catches up over Wi-Fi. If it persists for more than ~10 s, power-cycle the hub (unplug + plug back in). On reboot, the hub re-reads its NVS and the display matches the app.
After "Remove Hub", the hub didn't return to setup mode power-cycle while online
Remove Hub factory-resets the hub over the air, then evicts it from Apple Home. If the hub was offline at the moment you tapped Remove, it keeps its old configuration. Power-cycle the hub while it's on Wi-Fi — Remove Hub already wrote the eviction to the cloud, so the hub will see it on reconnect, factory-reset itself, and come back in setup mode. (Physical fallback: Settings → Re-Setup on the hub's touchscreen.)
Hub shows "Setup mode" after a router or SSID change Wi-Fi creds in NVS · re-provision
The hub remembers Wi-Fi credentials in NVS. After a router/SSID change, tap the touchscreen once to re-enter setup mode. Open the Locksure app — the hub appears in the "+" wizard; tap and provide the new Wi-Fi credentials. (If the hub isn't responding to a tap at all, long-press the touchscreen for a full factory reset, then start over.)
Hub display is upside-down after wall-mounting double-tap to flip 180°
Double-tap the touchscreen to flip the display 180°. The setting persists across reboots.
DAY_TO_DAY_OPERATION
Lock slow to come online after adding a hub internal session list full · power-cycle clears it
Most locks come online within ~20 s of the hub being added. If the door tile on the hub stays on the spinner longer than a minute, the hub will show a "Lock not responding — power-cycle the lock" hint. After lots of pair/unpair activity, the lock's internal session list can fill up and it stops responding to new connections for a while. A power-cycle (battery out + in for a couple of seconds) clears this immediately — the hub attaches within a few seconds.
Shared user can't see live state door needs to be on a hub
- Confirm the door is on a hub. Without a hub, sharing only delivers live state while the owner's app is open and within Matter/Bluetooth range of the lock — for hands-off sharing the door needs a hub.
- Both owner and shared user must be on the latest app build — older builds don't honour the "hub owns
rooms.state" rule and can fight the hub for the write. - If the door has a hub assigned and both users are on a current app build but state is still stale: confirm the hub is online (the door tile's hub-IP timestamp should be within the last 10 minutes). If not, power-cycle the hub.
Events arrive late or in the wrong order ring-buffer back-fill on reconnect
The Locksure Monitor keeps a 64-event ring buffer on-device. Your phone back-fills from it on every connection. Open the Locksure app and pull-to-refresh on the History tab — timestamps reconcile against the device's anchored boot-epoch clock so every event has the same wall-clock time on every phone. (Heads-up: at very high event cadence the on-device ring wraps in ~3–4 minutes, so events older than that can be lost if nothing has synced in the meantime. Adding a Locksure Hub keeps everything archived to the cloud.)
I see two notifications for the same lock turn server-side dedup · refresh history
This was a duplication bug fixed in the production app build. Pull-to-refresh the History tab — the older app-side notification gets coalesced into the canonical history-sync entry within seconds. If you're still seeing duplicates on a recent build, confirm the door has a hub assigned and check that you're not running two app instances on the same account simultaneously.
Geofence isn't triggering when I leave home needs "Always" location permission
iOS: Settings → Locksure → Location → "Always". Android: Apps → Locksure → Permissions → Location → "Allow all the time". Without "Always" / "All the time", the OS won't run our geofence in the background. The disclosure dialog explains this on first toggle. Geofence alerts also need a Locksure Hub — the hub publishes live door state to the cloud so the alert can fire even with the app closed.
Battery drops faster than expected TX power · cold temperatures · reading accuracy
Check the TX power level in the per-door bottom-sheet. Default is level 2 (+2 dBm); if your hub or Thread border router is far away you may have been bumped to level 3 or 4 — drop back to level 2 if range still works. Cold temperatures (under 5 °C) noticeably reduce a CR2032's deliverable capacity. The "temperature" field on the door tile shows the actual reading. Note also: the in-app battery percentage currently under-reads slightly at the high end of cell life — a brand-new CR2032 may show 80–95% rather than 100%. This is cosmetic and addressed in a future OTA.
Firmware update gets stuck at "Updating..." BLE proximity · retry-safe
Stay within BLE range of the Locksure Monitor (typically within 5 m). Don't put the phone to sleep. If the update still doesn't progress in 2 min, kill the app, re-open, and retry. The DFU pipeline is fully retry-safe — partial uploads are discarded, and the loader has a 120-second stall watchdog that reverts to the previous image automatically if BLE goes quiet.
Clearing notification history but events seem to come back on-device log lag
Settings → Clear Notification History removes the events from your timeline. If the list still appears immediately after, pull to refresh / leave and re-open the History tab — the screen can lag the delete by a moment. Known limitation: clearing removes events from your account, but the lock's on-device event log isn't always wiped at the same time, so a full re-sync after an app reinstall could resurface old events. Addressed in a future OTA.
What you can trigger from a lock event
Once the Locksure Monitor is paired into Apple Home, Google Home, SmartThings or Home Assistant, every lock + door event becomes a trigger for that platform's automation engine.
Apple Home automations
"When the front door unlocks after sunset, turn on the hall lights at 30% for 2 minutes." Also works with Focus modes (silence work calls when the door's unlocked = somebody's home).
Google Home Household Routines
"When the back door opens, announce on the Nest Hub kitchen." Or chain with presence: "If everyone's left and a door is still unlocked, push a reminder to Mum's phone."
Alexa Routines
"Alexa, is the front door locked?" — voice query works on every Echo. Routines can trigger from lock/unlock/open as a sensor.
Home Assistant YAML
Both endpoints (Door Lock + Binary Sensor) appear automatically. Build any conditional you like — we've published 4 ready-to-paste examples (link in Learn More).
Common questions up front
Is this a Matter-certified product?
Built on Nordic Semiconductor's CSA-certified Matter-over-Thread platform. Full CSA product certification is in progress and rides the OTA pipeline as a free signed update once the audit completes — at which point the "Uncertified Accessory" warning goes away on Apple Home. Early-bird units ship Matter-compatible from day one.
Can it unlock my door remotely?
No. 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 — by design.
How is this different from the Aqara U200 / U200 Lite?
Correction (30 May 2026): earlier copy on this page mis-framed the U200 as cylinder-replacement. It isn't — the U200 is a retrofit that mounts over your existing thumb-turn, same install style as Locksure. Thanks to the Reddit user who flagged it.
The real difference is that the U200 motorises the thumb-turn so it can lock and unlock remotely, whereas Locksure reports the state without an actuator. That gives the U200 remote unlock (which Locksure cannot do, by design) at the cost of a Li-ion recharge every ~6 months (vs Locksure's CR2032 at ~2 years), a remote-unlock attack surface, no contact-sensor endpoint for door open/close, and a £128 (U200 Lite) to £180 (U200) price tag vs Locksure's £55.99 early bird (£79.99 RRP). If remote unlock matters to you, the U200 Lite at £128 is a fair price for what it does — we don't compete in that category. If lock-state monitoring on a 2-year battery with no actuator and no recharge cycle is what you need, Locksure is the cheaper, lower-attack-surface choice.
Do I need a Locksure Hub?
Not to use the sensor with Apple Home / Google Home etc. — for that you just need a Thread border router on your network (any Apple TV 4K, HomePod mini, Nest Hub 2, Echo 4th gen, eero 6+, etc.). The Locksure Hub is required, however, for the three premium Locksure-app features: door sharing (any sharing — invite a family member by email), longer event history (months instead of the device's on-board 64-event ring), and geofence alerts ("door left unlocked when I left home"). Plus the Hub adds the at-a-glance touchscreen display.
How is this different from an Eve / Ring contact sensor?
A contact sensor only tells you whether a door is open or closed. It cannot detect whether the lock is engaged. The Locksure Matter sensor reports both lock state and door position as two independent Matter endpoints in one device.
Does it work with Home Assistant?
Yes. Home Assistant supports Matter commissioning natively from version 2023.12. The sensor exposes both a Door Lock entity and a Binary Sensor entity for door position.
Battery life?
1 × CR2032 lithium coin cell. ~2 years of typical use at the lowest TX power setting (level 1). The app reports estimated remaining battery and warns at <10%.
Deeper guides on Matter lock sensing
Five in-depth guides covering each major platform — Apple Home, Google Home, Home Assistant — plus a fitment guide and a "Matter door sensor vs contact sensor" explainer to clear up the search-result confusion.
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 →