1. Logitech Logi Circle ($200)

This petite security camera outperformed 40 others in experts' tests. Setup is "ridiculously simple," and the device alerts your smartphone when it detects movement. Twenty-four hours of footage can be saved to the cloud for free. Buy it at Amazon.

2. Icontrol Networks Piper NV ($280)

Like the Logi Circle, the Piper NV offers sharp night vision, two-way audio, and live video streaming. It can also sound a siren, monitor temperature, and double as a smart-home automation hub. Buy it at Amazon.

3. Arlo Pro ($250)

This wireless, weatherproof outdoor camera can detect movement up to 23 feet away. Once it alerts you to an intrusion, you can use your phone and the Arlo's speaker to issue a verbal warning. A 100-decibel siren is your backup. Buy it at Amazon.

4. August Smart Lock ($229)

A smart lock ends the need for a key, giving your smart phone the same power. Reliable and "extremely easy to install," the August can be set to unlock a dead bolt as you approach the door and re-engage it when you leave. Buy it at Amazon.

5. SkyBell HD ($199)

This high-definition doorbell camera makes it easy to know who's waiting at your threshold. When a visitor rings, SkyBell notifies your phone, pulls up a live video, and lets you talk to the person remotely — if you want to. Buy it at Amazon.

Editor's note: Every week The Week's editors survey product reviews and articles in websites, newspapers, and magazines, to find cool and useful new items we think you'll like. We're now making it easier to purchase these selections through affiliate partnerships with certain retailers. The Week may get a share of the revenue from these purchases.