Best 5 Smart Smoke Detectors of 2026: Smoke and CO Alarms With App Alerts

The First Alert SC5 is the closest thing to a successor for the Nest Protect, and for many households it is the easiest smart alarm to recommend. It combines a photoelectric smoke sensor with an electrochemical CO sensor and uses First Alert's Precision Detection technology, which the company says is designed to meet updated standards for early warning and fewer nuisance alarms, such as those triggered by cooking. The product page lists compliance with the UL 217 10th Edition standard.

When something is wrong, the SC5 speaks: voice alerts with a Heads-Up warning name the type of danger and its location in the home, and the First Alert app sends mobile notifications whether you are home or away. Alarms interconnect wirelessly, so when one sounds, compatible alarms elsewhere in the house sound as well. That compatibility explicitly includes Google Nest Protect units, which means you can replace aging Protects one at a time without breaking your existing network.

The battery version runs on replaceable CR123A lithium cells and warns you in the app before they run low, which removes the classic late-night chirp. First Alert backs it with a 10-year limited warranty. The main caveats are that CR123A batteries cost more than AA cells, and if you rely on the Nest Protect pathway, setup runs through the Google Home app and a Google account. A hardwired SC5 is also sold for homes with existing alarm wiring.

Many American homes already have a chain of hardwired, interconnected smoke alarms in the ceiling, and a lot of those are Kidde. The P4010ACSCO-WF is built for exactly that situation. Kidde says it is designed to work with existing Kidde hardwire interconnected alarms, so when any alarm in the chain goes off, even one without smart features, all of them sound and the smart unit sends a phone notification. In other words, swapping just one alarm can make the whole system report to your phone.

It is a combination unit with a photoelectric smoke sensor and an electrochemical CO sensor. In an emergency it sounds an 85-decibel alarm and calls out the hazard: Fire for smoke, Warning Carbon Monoxide for CO, and it announces when the unit has reached the end of its life. The Kidde app delivers real-time alerts and can notify friends and family, and the alarm is listed as compatible with Amazon Alexa and Google Home.

Because it is hardwired, installation means working with a 120V ceiling box, which some owners will prefer to leave to an electrician. It also does not name the room in its voice alerts the way the First Alert SC5 does. Kidde backs the alarm with a 10-year limited warranty. If you already have Kidde hardwired alarms, this is the most direct and least disruptive way to add smart alerts.

Kidde and Ring teamed up on this alarm so that smoke and CO events land in the same app as your doorbell, cameras and Ring Alarm sensors. Setup runs through the Ring app and does not require any other Ring hardware, but if you already have Ring devices, keeping everything in one place makes it much easier for every household member to see what is happening.

The RGCUAR-RW is a hardwired 120V alarm with two AA backup batteries, and it connects over 2.4 GHz Wi-Fi. Voice alerts explain why the alarm is sounding, and the app sends real-time notifications for smoke, CO and low battery. Kidde notes that adding one smart alarm to existing Kidde hardwired alarms can bring app notifications to the whole chain. The standout feature is optional 24/7 smoke and CO monitoring through a Ring subscription, in which trained agents can request emergency help when an alarm triggers, a meaningful upgrade for anyone who travels.

There are a few things to know. Kidde specifies particular AA battery brands for backup and advises against lithium AAs, so read the manual before swapping. Wi-Fi and full operation depend on AC power, with the batteries serving as backup. Professional monitoring is limited to US addresses and is a paid add-on. Kidde also sells a battery-only Ring version (RGCUDR-RW) for homes without wiring.

X-Sense takes the base-station approach. Each XP0A-MR combination alarm runs on a replaceable battery and talks to an SBS50 Base Station, which connects to your 2.4 GHz Wi-Fi and relays alerts to the X-Sense app. Because the alarms communicate wirelessly with the base, you can interconnect alarms across a large or multi-story home without running any wiring, which is the biggest reason to choose this system for older houses, additions and long ranch layouts.

X-Sense lists a 1,700-foot wireless range for the system, a long reach for detached garages or finished basements. When an alarm triggers, it speaks the hazard and its location, and the app sends a real-time notification along with low-battery warnings. X-Sense also offers an optional fire dispatch service and lists Home Assistant compatibility, which will appeal to tinkerers who want their alarms inside a broader automation setup.

The tradeoffs are mostly about ecosystem and documentation. Everything depends on the SBS50 base station, so a power or Wi-Fi problem there affects app alerts, although the alarms still sound locally. X-Sense's warranty is described as up to five years, shorter than the 10-year coverage from First Alert and Kidde. If you want many interconnected battery alarms without an electrician, this kit delivers the most coverage for the effort.

The XP0A-iR is X-Sense's answer for people who want phone alerts without buying or placing a base station. Each alarm connects directly to your 2.4 GHz Wi-Fi network and reports to the X-Sense app, so a single unit in an apartment hallway or a small house can be up and running in minutes. Multi-packs make it straightforward to cover several bedrooms and a kitchen area at once.

Feature-wise it keeps the essentials that make smart alarms worth buying: combination smoke and CO detection, a voice alarm that announces the location, real-time app alerts and low-battery warnings through the app. It runs on a replaceable battery, so there is no wiring and nothing to install beyond a ceiling mount, which also makes it a sensible choice for renters who can take the alarms with them when they move.

The compromise is that it sits outside X-Sense's base-station ecosystem: the XP0A-iR is not compatible with the SBS50, so you cannot mix it into an existing XP0A-MR network. Buyers should check how interconnection works across their specific multi-pack before relying on it for whole-home coverage. Battery life with direct Wi-Fi is also typically shorter than with low-power base-station designs. As an affordable, simple entry into smart smoke and CO alerts, though, it fills the role well.