Amazon Key smart lock features are available across the US

In-home deliveries are still limited to 37 cities in the US though.

Amazon Key is a relatively new smart lock service that allows delivery people to enter your home (they're monitored, of course) and leave packages. Users can also grant entry to certain people while they're away, as well take advantage of keyless entry for themselves. The service automatically records what's happening, so you know exactly what the dog walker is doing when they pick up your animals. Now, Amazon has announced that Key features are now available across the US, but the in-home delivery is still only available in 37 select cities and surrounding areas.

The service uses a smart lock and connected camera, along with an app, to provide home access to guests. Of course, the highly touted feature is being able to take deliveries when no one is home. When a delivery person has a package, they can scan the barcode, which will unlock the door. The entire thing happens through an app, and it's recorded, so you know exactly what is happening while the courier is in your home. After they leave, they simply lock the door, and that's it.

Customers can choose from eight different smart locks (including five more options added today) that are available from leading manufacturers, like Kwikset and Yale. And right now, Amazon is running a promotion where users can receive anywhere from $110 to $140 off of a Amazon Key Home Kit, depending on which one you choose.

Since Amazon is now offering some Amazon Key features across the US, it's probably only a matter of time before the company expands in-home deliveries to more cities as well. There are certainly some privacy concerns with the service, but the company introduced fingerprint authentication back in March, so that should certainly help with some of the hesitation.