Which kind of spy camera detector do you actually need?

Handheld RF detectors

What it measures: radio energy from nearby transmitters. A handheld RF detector has an antenna and a broadband receiver, and it beeps or lights up more strongly as you get closer to an active source. Typical consumer units claim coverage from a few megahertz up to several gigahertz, which spans most wireless video links, though sensitivity varies a lot across that range.

Catches: wireless cameras and bugs that are transmitting while you sweep, including ones on a network you cannot join or using a cellular connection.

Misses: cameras that record to a memory card without transmitting, devices that send in short bursts between your passes, and anything switched off. Trade-off: homes and hotels are full of phones, routers, smart speakers and TVs that trigger the same alarm, so an RF detector is most useful in a room where you can switch off or account for the normal sources. Our RF detector guide goes further.

Lens-finder viewers

What it measures: light reflected back from a lens. These are small viewers with a ring of flashing red LEDs around a red-tinted window. You look through the window while the LEDs light the room; a camera lens returns the red light as a bright, sharp dot, while the filter darkens most other surfaces.

Catches: cameras of every kind, on or off, online or offline, as long as the lens faces you. Misses: lenses out of your line of sight, very small recessed pinholes at the edge of range, and lenses behind tinted covers. Trade-off: it is cheap and simple, but it takes practice, and reflective screws and glass produce false alarms. A phone flashlight does a similar job with a little less contrast.

Combo units

Many handheld gadgets put an RF detector and a lens-finder window in one body, and some add a magnetic sensor for finding tracker magnets or electronics. Catches: the union of what the parts catch. Misses: the same gaps as each part, and the individual functions are often less sensitive than a dedicated tool. A combo unit is a convenient travel item rather than a better detector.

Professional counter-surveillance sweeps

Specialists bring equipment and method that consumer gadgets cannot match. Spectrum analyzers show exactly which frequencies are active and can be left running to catch devices that transmit only now and then. Non-linear junction detectors find semiconductor components inside walls, furniture and objects whether the device is powered or not. Thermal imaging, physical inspection of wiring and ceilings, and network audits usually complete the picture.

Catches: far more than any handheld tool, including audio bugs and switched-off electronics. Misses: very little in skilled hands, though no sweep can promise a space is clean. Trade-off: it is expensive relative to the other options and needs access to the space. It makes sense for a business, a legal dispute, a stalking concern, or anywhere you have reason to think someone skilled is involved.

Phone apps

What it measures: whatever the phone's own hardware can sense. A phone has no broadband RF receiver, so an app cannot act as an RF detector, whatever its listing suggests. What it can do is use the flashlight and camera for lens reflections and infrared light, the Wi-Fi radio to query the local network, the Bluetooth radio to list nearby devices, and the magnetometer to notice electronics.

Candor, an Android app, runs all four of those checks. Its Wi-Fi camera scan looks for devices on the joined network that answer camera discovery requests or offer video stream ports, and gives a plain reason for each flag. It does not find audio-only bugs.

Catches: many consumer Wi-Fi cameras on a shared network, visible lenses, some night-vision cameras, and Bluetooth devices. Misses: cameras on another network or mobile data, offline recorders out of your line of sight, and anything the phone's sensors cannot read.

When a phone app is enough

For a traveler checking a hotel room or short-term rental, a phone app plus a careful manual search covers the most common threat: a cheap consumer camera, often on Wi-Fi, aimed at a bed or bathroom. The phone detector app guide explains how to run a full sweep.

Add a dedicated RF detector if you regularly stay in places where you can switch off known transmitters and want to catch cameras on networks you cannot join. Go professional if you suspect a targeted setup, audio bugs, or someone with the skill and access to hide equipment inside walls.

Frequently asked questions