The Best Home Security System Is Modular (2026)

One morning, about seven years ago, I awoke to the sound of my cell phone buzzing on my bedside table. As I sat up and the world slowly began to come into focus, I heard a high-pitched siren—something I had never heard in our year of living in the house—coming from somewhere downstairs. I answered my phone.

“Hello, this is Officer [redacted] from the [my town’s] Police Department. I understand there’s been an emergency?" asked a man’s voice, a car engine revving in the background. "Do you need assistance?” Just then, my kindergarten-age son burst through our bedroom door in a panic.

Apparently, he had woken up early, gone into the garage for some reason lost to time, triggered the alarm, and forgotten our garage's smart lock code to get back inside the house. He eventually remembered, but it was too late. An agent with our home security system, SimpliSafe, called to see if it was a false alarm, and, after receiving no response, dispatched the police.

I immediately explained the situation to the officer, saving him a trip to the house, but I was heartened to know my security system, which I had installed myself in minutes with no tools when we first moved in, had done its job. Even so, the event rattled me enough to inspire an up-leveling in our setup.

In the years that have passed since that morning, I've expanded my SimpliSafe system. I now have a smoke alarm listener for our hardwired network of smoke alarms, a smart CO2 detector, an outdoor camera with a monitoring plan, and an additional smart lock that I added to my front door.

All of these add-ons were easy for me to install myself and did not add to the monthly monitoring fee, which is also not locked into any length of contract, unlike competitors like ADT. My SimpliSafe journey hasn't been entirely smooth sailing, especially with the smart lock and outdoor camera (more on that below), but if you’re intimidated by the idea of owning or installing a security system, SimpliSafe and its DIY ecosystem may be up your alley.

Taking Care of Business

SimpliSafe

8-Piece Wireless Home Security System

The heart of the SimpliSafe system is its base station, which looks a bit like an essential oil diffuser, plus a keypad, from which you can arm and disarm the alarm and monitor add-on components. You can also do this using the connected app. I keep the base tucked away in a cabinet, but you can situate it anywhere with an outlet (it also operates on battery backup in case of a power outage), and mount the keypad near a door with the included adhesive strip. The system is compatible with Amazon Alexa and Google Home and runs on 2.4-GHz Wi-Fi.

There are two base starter packages—an Indoor and Outdoor version—and each includes the base station and keypad. The Indoor comes with a motion sensor, a yard sign, and three door or window entry sensors, all of which are installable with adhesive strips and come with batteries that last for years. When the sensor is triggered—even if the alarm is unarmed—a chime will sound from the base station. If you have young kids who have just learned to open doors themselves, you will especially love this feature. You can also add additional entry sensors at any time, which is as easy as peeling off adhesive strips and pressing Add Device in the app.

The Outdoor starter package comes with all of the above, plus an outdoor camera instead of the motion sensor. I admit I don’t love SimpliSafe’s cameras (additional outdoor cameras are available separately for $200). If you receive an alert and want to see what’s going on, expect a lag: The camera can take 30 seconds or even longer to “wake up,” which is a long time if you want to catch someone in the act or monitor an activity.

However, I do like the outdoor camera’s Active Guard Outdoor Protection add-on, especially since we park our cars in our driveway overnight. The feature uses an AI algorithm to flag anything out of the ordinary for your property (between 8 pm and 6 am for the second-tier plan, and 24/7 for the top-tier plan, with a pricing breakdown for each below) to a live agent. The agent will then confirm whether it’s a “familiar face” (yes, it does use biometric data) or a sanctioned activity (perhaps an early-morning Amazon delivery) and, in either of those cases, will send an email report.

If the agent detects an unfamiliar face or suspicious-seeming activity, they will talk to the unknown person through a speaker on the camera, and, if necessary, shine a light and activate a siren. Unlike with a generic alarm, if a SimpliSafe agent can confirm a crime in progress, they also have the authority to expedite police response. Note that the camera does need to be plugged into an outlet at all times if you're using the Active Guard Outdoor Protection feature, but this isn't unusual for home security cameras.

I have the outdoor camera pointing at the driveway to make the most use of the Active Guard. But for cameras elsewhere on our house's exterior, I supplemented our SimpliSafe setup with Arlos—top pick in our guide to the Best Outdoor Security Cameras—which are far less laggy. (Note that Active Guard face matching is not available in Texas, Illinois, or Portland, Oregon, as these areas require explicit consent for biometric data collection.)

Do You Hear What I Hear?

• Photograph: Kat Merck
• Courtesy of Best Buy

SimpliSafe

Smoke and Carbon Monoxide Alarm Listener

Perhaps my favorite of all the SimpliSafe add-ons, however, is the smoke and carbon monoxide alarm listener. Smart smoke alarms (including SimpliSafe’s model) typically use only photoelectric sensors, which are designed to detect only smoky, smoldering fires. Alternatively, hardwired “dumb” smoke alarms typically include both photoelectric and ionization sensors, making them more likely to detect both thick smoke and fast-moving flames. This means that if you have only smart smoke detectors in your home, they may detect thick smoke and not flames. My colleague Nena Farrell confirmed this when she lit some paper on fire directly beneath a smart smoke alarm as a test and found that it did not sound.

The smoke alarm listener, however, lets you have it both ways. You can use your dual-sensor dumb smoke alarm but have it become smart by placing the listener next to the smoke alarm located nearest the base station. The device will “listen” for the alarm to sound—if it hears the alarm, it will alert you through the app in addition to agents at SimpliSafe’s monitoring center. Tests and battery chirping don't trigger it, so you’ll only get a notification for the real deal.

SimpliSafe's smart lock is also a worthwhile add-on, as arming the system will automatically lock the deadbolt if you forget to lock your door. It’s also nice to be able to come in and out without a key. The installation is involved, though the directions are excellent. The lock itself is a little finicky; it's lost connection with the keypad and needed to be recalibrated several times in the six months I’ve had it, but I would buy another one if it broke, as I like my door lock being connected to the system.

• Photograph: Kat Merck
• Courtesy of Best Buy

SimpliSafe

Smart Lock Series 2

Mod Style and Prices

Because SimpliSafe’s whole ecosystem is modular, any component can be added on at any time, within minutes, and usually without tools. Basic monitoring 24/7 when the system is armed is $1.10 a day; this plus Active Guard Outdoor Protection 8 pm to 6 am (when the system is armed) is $1.66 a day; and 24/7 basic monitoring and Active Guard Outdoor Protection is $2.66 a day. Thirty-day cloud storage is included. It’s also easy to go up or down a tier if your needs change; there are no cancellation fees, and I have had nothing but good experiences with SimpliSafe’s customer service, whose agents have never tried to upsell me.

Additional accessories include all of the previously mentioned (adding more sensors or cameras is just a matter of pressing Add in the app), plus glass-break sensors, a doorbell camera, a wireless indoor camera (which I have, but I prefer the older hardwired version), a water sensor, and a temperature sensor.

While SimpliSafe’s outdoor camera still lags behind competitors (like Arlo), and some add-ons (like the smart lock) are close to being more trouble than they're worth, this is still one of the easiest and most flexible DIY security setups out there. The fact that I’ve only continued adding to it over nearly a decade should be endorsement enough of its utility.

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