Check a changing room or toilet in under a minute
Fitting rooms, gym showers, pool cabins and public toilets. Two quick checks before you undress, completely free.
Before you start
In a changing room you only have a minute, and the risk is a mirror or a lens you can’t see. Hidden Eye’s changing-room check is made for exactly that: a fingertip test for two-way mirrors and a quick flash sweep for lenses.
Both checks are free, work without any network and need nothing but your phone.
In July 2026 South Korea made hidden-camera detection systems required equipment in public restrooms. Source: The Star / ANN
Where cameras hide
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The mirror
A two-way mirror lets someone watch or film from the other side. It is the first thing to test.
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Ceiling corners and lights
High spots with a view of the whole cabin.
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Air vents and grilles
Slats are easy to hide a lens behind.
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Coat hooks and shelves
Small objects screwed to the wall at body height.
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Smoke detectors and sensors
A sensor in a tiny cabin deserves a second look.
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Hand dryers, soap and paper dispensers
In toilets and showers, anything mounted on the wall facing you.
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Gaps under doors and partitions
A phone or camera can be held under or over a partition.
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Holes in walls and ceiling tiles
Small holes that don’t belong to a screw or a fixture.
How to check, step by step
4 steps in the app · Under a minute
- 1
Do the Mirror Test
Touch the glass with your fingernail. A gap between your nail and its reflection means a normal mirror; if they touch directly, it can be a two-way mirror.
- 2
Check behind the glass
With the lights off, hold your flash against the mirror. If you see a room or space behind it, don’t use the cabin.
- 3
Sweep with the Lens Finder
Move your phone slowly around the walls, ceiling and fittings. A lens reflects the blinking flash and gets circled.
- 4
Look at the spots on the checklist
Vents, hooks, detectors and holes. The app shows each one with a short tip.
What Hidden Eye does for you
The app picks the right checks for this place, tells you where to hold your phone and what each result means.
Mirror Test Free
A fingertip test that tells a normal mirror from a two-way one.
Lens Finder Free
The flash blinks; any tiny spot that blinks back is a lens, and the app circles it.
Good to know
- The whole changing-room check is free, including the report.
- It works offline, so you can use it in basements and gyms without signal.
- If a mirror looks wrong, cover it with a towel and tell the staff, or use another cabin.
Found something?
Don’t touch it. Photograph it, cover it, and report it. Our step-by-step guide has a ready message and your local emergency number.
What to do nowQuestions
How do I know if a mirror is two‑way?
Put your fingernail on the glass. On a normal mirror there is a small gap between your nail and its reflection, because the silver is behind the glass. On a two-way mirror the nail and its reflection touch. Then check with your flash in the dark: you may see the space behind it.
Is the changing room check free?
Yes. The Mirror Test, the Lens Finder and the full changing-room check with its report are free.
Does it work in places without signal?
Yes. Both checks run entirely on your phone.
More guides
Next room, changing room or car? Check it first.
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