Thread devices are invisible by design. They just work — until one doesn't, and nothing will tell you why. ThreadMapper maps every device, grades every room, and says plainly which of its numbers are readings and which are estimates.
The problem
A sensor stops reporting. An hour later it comes back. Your hub says everything is fine, because from where it stands everything is. The information that would explain it — signal, routing, what else was on the air — is never shown to you at all.
An A–F score with the specific issues pulling it down, not just a number.
Every device grouped by room, showing how each one reaches a border router.
Walk a room, get a coverage grade. Drivable from your wrist so both hands stay free.
Know the moment a device drops, with a grace period and quiet hours you set.
30 days of signal trend, uptime and firmware changes for every accessory.
Grade and complications on the wrist; a proper sidebar layout on iPad, not a stretched phone.
Where those tags come from
iOS gives third-party apps no radio signal strength for Thread accessories, no parent-child relationships and no routing table. Any app showing you dBm for a HomeKit device is showing you something it cannot read.
ThreadMapper measures how quickly each accessory answers, calls that an estimate wherever it appears, and infers the mesh layout from what HomeKit does expose. It works, and it is honest about being an inference.
An OpenThread Border Router alone does not fix this.
Its REST API reports real network facts — name, channel, PAN ID — and ThreadMapper uses them. But we tested its diagnostics endpoints against a live two-node mesh: the requests complete and return nothing usable. Per-node routing is not available that way, whatever the documentation implies.
Which is why the probe exists.
The probe
Run a lightweight agent on a Raspberry Pi with an 802.15.4 dongle and it joins your Thread mesh as a real node. From inside, everything the phone cannot see becomes readable — and because it never sleeps, it sees the 3 a.m. failures you don't.
A waterfall of the whole band. You can see the microwave at dinner and the neighbour's Wi-Fi in the evening.
Departures lined up against noise and radio error counters — with the readings shown, and “no clear cause” when there isn't one.
What happened since you last opened the app. Silent when nothing did.
Transmit retries and channel-busy failures — congestion shows here long before anything looks offline.
The agent is open source and runs on a Raspberry Pi 4 or 5 you may already own — the 802.15.4 dongle it needs costs about $10–25. Setup guide →
Read that first: a Raspberry Pi has no Thread radio of its own, and joining an existing Apple or Google mesh needs credentials those platforms don't yet let you export. It is not a product you can buy — it's a build.
In the app
Privacy
Signal history deliberately doesn't sync.
Readings depend on where the device taking them is standing. Merging an iPad in a drawer with an iPhone in your pocket would produce a history describing a place nobody is. Notes and settings sync; measurements stay put.
Pro
Probe features aren't behind the paywall.
If you've gone to the trouble of building a probe, hitting a second paywall would be a poor way to say thank you. Everything the probe unlocks is included.
No install needed
Scan a code or open a link and a small slice of ThreadMapper runs without installing the app. It grades a simulated home with the same engine it would use on yours — twelve devices, two border routers, one offline, one on a failing battery — and says before anything else that every number in it is simulated. An App Clip may not read Apple Home or your local network, which is where the real app's numbers come from. Free.
Getting started
A home with at least one Thread border router — a HomePod mini, Apple TV 4K or similar — since ThreadMapper reads your network through HomeKit. AI features need iOS 26 on an Apple Intelligence–capable device. The probe is entirely optional.
Want to look around first? Turn on Demo Mode and the whole app runs on a simulated network — no hardware, no HomeKit, nothing to set up.
