Choosing the right disguise
Pick the object that already suits the room. A clock or a charging dock belongs on a desk or a bedside table. A smoke detector belongs on a ceiling and gives the widest view of a room. A bluetooth speaker suits a lounge or an office shelf. A power bank or a book sits anywhere and is never questioned.
Mains-powered disguises are the practical choice for long-term monitoring, since a charger or clock camera is plugged in anyway, so it keeps recording without anyone changing a battery. Battery models suit rooms with no convenient socket, or short-term use.
Live viewing
WiFi models stream to a phone app so you can check in from anywhere and get an alert the moment motion is detected. Offline models record to a memory card, which is simpler and leaves nothing on a network.
For cameras you carry rather than place, see wearable cameras. For the smallest bodies, see mini spy cameras. To browse everything, see all spy cameras.
Mains or battery, and what each one costs you
A camera built into something that is already plugged in, a charging dock, an alarm clock, a speaker, a smoke detector, keeps recording without anyone touching it. That is the practical choice for anything running longer than an afternoon, and it is why those four objects dominate this category.
A battery unit goes where there is no socket, at the cost of runtime. Recording continuously, expect one to three hours. Recording only on motion, expect days in a quiet room and hours in a busy one, because every trigger wakes the camera and the battery drains in proportion to how much happens in front of it.
Live view, or recording you collect later
A WiFi model joins the home network and streams to your phone, so you can look now and get an alert when something moves. It needs a network within range and it needs that network to stay up.
A card-only model records to internal storage and tells you nothing until you retrieve it. That sounds worse and often is not: there is no network for anyone to notice the device on, no app, no account, and nothing to fail. If the point is a record rather than a live watch, card-only is the more reliable answer.
Placement decides more than specification
A camera sees a cone, not a room. A wide lens on a shelf covers a whole lounge. A narrow lens covers a doorway and misses the sofa. Decide what you actually need to see before you decide what to buy, because a 4K camera pointed at the wrong third of the room is worth less than a 1080p one pointed at the right third.
Height matters too. Chest height gives faces. Ceiling height gives movement and the top of heads. A smoke alarm gives the widest coverage of a room and the worst view of anyone's face.
What people notice
Not lenses. Objects that have moved, objects that have appeared, and objects pointed somewhere odd. A charger plugged in behind a bedside table is invisible. The same charger sitting in the middle of an empty shelf is the first thing a visitor looks at.
Common questions
Will it look obvious? Each one is a working everyday object, a clock, a charging dock, a speaker, a smoke detector, a power bank, and it functions as one, with the lens built into the housing.
Can I view it from my phone? On most models, yes. Offline models record to card instead.