Know when police gear is near — anywhere in Massachusetts.
From Boston (pop. 653,833) across all 50 of its biggest cities, Massachusetts law-enforcement gear broadcasts Bluetooth and Wi-Fi signatures everywhere it goes. Cop Spotter listens for them — green means clear, red-and-blue means near.
Built in small batches. No subscription. No account.
Coverage across the state.
Pick your city for local coverage.
Suffolk County · pop. 653,833
Suffolk County · pop. 571,281
Worcester County · pop. 206,518
Hampden County · pop. 154,341
Middlesex County · pop. 110,699
Middlesex County · pop. 110,402
Bristol County · pop. 101,079
Suffolk County · pop. 97,826
Plymouth County · pop. 95,314
Bristol County · pop. 94,000
Norfolk County · pop. 93,618
Essex County · pop. 92,457
Middlesex County · pop. 88,817
Middlesex County · pop. 80,318
Essex County · pop. 80,231
Middlesex County · pop. 68,318
Middlesex County · pop. 65,413
Middlesex County · pop. 63,378
Essex County · pop. 62,765
Middlesex County · pop. 61,068
Norfolk County · pop. 58,732
Middlesex County · pop. 57,403
Bristol County · pop. 56,789
Hampden County · pop. 56,741
Hampden County · pop. 55,179
Norfolk County · pop. 54,395
Suffolk County · pop. 53,422
Essex County · pop. 52,504
Essex County · pop. 52,044
Essex County · pop. 50,293
Barnstable County · pop. 47,821
Middlesex County · pop. 46,050
Suffolk County · pop. 45,977
Bristol County · pop. 44,284
Berkshire County · pop. 43,303
Suffolk County · pop. 43,066
Essex County · pop. 42,869
Middlesex County · pop. 42,844
Hampden County · pop. 41,690
Worcester County · pop. 41,569
Essex County · pop. 41,186
Hampden County · pop. 40,684
Worcester County · pop. 40,545
Essex County · pop. 40,365
Middlesex County · pop. 39,904
Hampshire County · pop. 39,833
Middlesex County · pop. 39,818
Middlesex County · pop. 39,555
Suffolk County · pop. 39,398
Suffolk County · pop. 37,733
The signature database is built from public registries — Bluetooth SIG company IDs, IEEE hardware prefixes, and the known broadcast fingerprints of the gear itself.
Axon body cameras announce themselves over Bluetooth so docks can find them — including a hardware signature that survives the address rotation newer cameras use to hide. If a bodycam is close, Cop Spotter knows.
Tasers and Axon vehicle gear broadcast their own Bluetooth identities. Same family, same tell — the spotter matches them against the verified Axon signature set.
Flock safety-camera accessories — extended batteries, setup hotspots — leak recognizable Bluetooth names and Wi-Fi hardware prefixes. Cop Spotter watches both radios.
Modern police radios carry Bluetooth for mics and earpieces, and their hardware shows up in the air with manufacturer fingerprints. A radio match strobes the light exactly like every other gear type — nothing is second-class.
AirTags, SmartTags, Tiles and other tracking tags call home over Bluetooth. Cop Spotter listens for them too — when one is close enough to be traveling with you, the light pulses purple, and the pulse quickens as you get closer, so you can walk it down.
Skimmers hidden inside pumps and card readers phone home through cheap Bluetooth serial modules — and those modules advertise. When one is close, the light blinks amber before your card goes in.
Also in the database: Utility BodyWorn bodycams, Axon Fleet in-car systems, WatchGuard & Digital Ally in-car video, police drones (DJI and anything flying Remote ID), Stryker LIFEPAK ambulance monitors, Cradlepoint patrol-car routers, and Geotab fleet telematics — 103 verified hardware fingerprints in all.
No screen to read. One light tells you everything.
The board continuously scans Bluetooth and Wi-Fi broadcasts — the public advertisements devices send out so other equipment can discover them.
Every broadcast is checked against the signature database: company IDs, service UUIDs, hardware prefixes, and device names known to belong to police equipment, tracking tags, and skimmer hardware.
When a signature matches, the light answers in color — every gear type counts, radios included. Cooldowns between alerts keep the light meaningful instead of constant.
No modes, no menus — Cop Spotter listens for everything at once, and the color names what it heard.
Purple and amber only fire at close range — close enough to be on you or your car — so a crowd full of other people’s trackers doesn’t cry wolf.
Asked by buyers across Massachusetts.
Yes — it needs no network, app, or account. The signatures it matches are the same in Boston as in the smallest town in Massachusetts.
$50 one time — shipping included (U.S.), no tax added, no subscription, ever.
The 50 biggest cities in Massachusetts — listed below. The detector itself works anywhere in the state, page or no page.
Bodycams, Tasers, Flock camera accessories, radio gear, in-car video systems, police drones, LIFEPAK monitors, patrol-car routers, fleet telematics, hidden trackers, and skimmer modules — 103 verified hardware fingerprints.
Small batches, built to order.
The detector board, with the detection firmware loaded and the signature database installed. You add any USB-C power source — a power bank makes it pocket carry.
Buy now — $50Secure checkout via Stripe — shipping included, address collected at checkout (U.S.). Questions first? [email protected]
The same detector on your Android phone — all 103 signatures. It listens only, holds no internet permission, and collects nothing. Free, no account; the APK installs direct.
If it earns its keep, chip in: support goes straight into the next batch of boards.
Receive-only, by design. Cop Spotter listens to public broadcast advertisements that devices intentionally transmit for discovery. It does not intercept, decrypt, record, or interfere with any communication, and it transmits nothing.
Know your local laws. Rules around detection equipment vary by place. What the device does is legal in most of the U.S., but the responsibility for where and how you use it is yours.
No guarantees. Detection depends on the target gear being powered and advertising. This is an awareness tool, not a safety device.