Alarms & Sensors

Alarms and sensors are the least glamorous corner of a smart home, and for a renter they might be the smartest place to start. Everything here is cheap, everything runs on a battery, and almost everything sticks on with adhesive — which means you can cover a ground-floor window or an entry door tonight and peel the whole setup off clean on move-out day. Nothing gets drilled, nothing gets wired, and nothing your landlord would object to gets touched. That’s the entire appeal: real peace of mind with zero commitment and no hole to spackle when you leave.

There are two families of device here, and it helps to know which one you actually want. The first is the plain contact alarm — a magnet and a sensor that stick to a door or window and shriek the moment the two are pulled apart. It does one thing, loudly, and needs no phone, no app and no hub. The second is the smart contact sensor, which mounts the same way but sends a notification to your phone (and can nudge a light or a lock) when it opens. That’s the one to get if you want to know your door was opened while you were at work, not just startle whoever opened it.

For a door specifically there’s a third option that’s pure renter genius: a portable lock or a door-stop wedge that adds a second barrier without mounting anything at all. You place it by hand and take it away by hand, so it’s perfect for a dorm, a sublet, or a first-floor apartment where you want a little extra security at night. Because none of it is fixed to the door, there’s nothing to reverse and nothing to explain — and a portable lock adds a barrier a landlord’s master key can’t open.

Below are our two ranked roundups: the best door and window alarms for apartments, and a no-install dorm-room security kit that layers a portable lock, a wedge alarm and a shelf camera. If your worry is specifically a ground-floor or accessible window, our guide to apartment window security walks through the adhesive alarms and simple physical blocks that make a window harder to open. Every pick carries our Lease-Safe rating, and none of it leaves a mark.

One more family lives in this section and it isn’t about intruders at all: the sensors that catch a disaster while the apartment is empty. Our water leak detectors sit on the floor and shout before the neighbor’s ceiling does, and our smoke and carbon monoxide picks deal with the alarm you’re not allowed to touch — including the listener that forwards your landlord’s smoke alarm to your phone, and the plug-in CO alarm that needs no install at all.