If you don't want to spend a lot on these, I think the current best solution is based on Aqara and then smoke alarms by Life. We've been testing this for the past few months at our house and to make an alarm system, you can build an Apple Home system with parts from Aqara, Eufy, and First Alert, this assumes your current alarm system is flaking out and it is nice to see something that isn't proprietary.
The good news is that at the end of 2023, we are just in the transition to Matter and Thread, so you can now have the sensors that are standalone, and then the alarm system sort of disappears which is kind of nice. The right path seems to be to have a set of sensors, cameras, and motion devices, so what you really want to do is to get as much Thread and matter-capable devices for the long term:
For Apple Home, the door and window sensors.
- Aqara M2 Hub (with M3 coming later and do you really need one in the new Matter/Thread world). This is the hub for these sensors, we have the M1S and it has an alarm siren inside and also acts as a night light. I actually have the older M1S, but the M2 is better because it has 2.4GHz WiFi, Zigbee 3.0, and supports Matter now in a firmware upgrade. Upcoming is an M3 hub that will support Thread/Matter if you need it. They need something that is going to sound an alarm, so it depends if you want to use Apple Automation to do this and HomePods or want a dedicated hub.
- Aqara Zigbee door and Windows sensor. This is a device that is coin battery powered so that you can see which windows are open and closed. It is big, but it works. These things are getting pretty cheap too, and on Prime day are a remarkable $13 per sensor now which is pretty great. Note that it is smaller and cheaper and if you have a hub anyway, it may make sense to get this instead of the P2 below...
So you really want these thread and matter sensors, here are the ones I would recommend now. I'm going to try the Aqara Door and Window Sensor P2 and will report back:
- Aqara Door and Window Sensor P2 uses Matter and Thread so doesn't require a hub. This thing is butt ugly and is huge because it uses a 1,400MaH CR123 batter but the old sensor lasts two years, but the new one could be much better since no hub is required. But it does cost $24 on Prime Day.
- Eve Door & Window. The new one is a door and window sensor that is thread enabled, but I don't see it on the Apple or Amazon store anymore. It is $50 at Home Depot and looks pretty big.
- Tuo Contact Sensor. I have not seen this one reviewed, but it looks prettier but is $30 on pre-order right now.
Then for the fire alarm system, the First Alert I've tried but the pairing problems are big. So I might give the Owl Wired a try when I find a review of it.
- First Alert OneLink. This is a wireless system that is hard to get exactly right and synchronized, but once it is, it works well. There is a wired version and a completely wireless one called OneLink which we have. There are others as well.
- Owl Wired. There is also a wired system made by Owl Wired which uses USB C for power and has a battery backup, it is $169 direct, so this makes sense if you can get USB C power up into your attic or somewhere. It also works with existing alarm systems because it has a third wire, so a good replacement if you are upgrading your current panel
Monitoring as a Service
Note that none of these come with an alarm monitoring service. We've tried Simplisafe, but at $20/month with proprietary cameras, this is really not a good deal. What we want is an open-source system that uses just open cameras and sensors, but this doesn't seem to be available. So these systems are best if you don't need instant third-party alarms and can live with alerts from Apple Home.