The service allows you to choose to unlock your door, remotely.
Amazon bills it as a way to let delivery services, maintenance workers, and even friends or family, into your home, without leaving a physical key.
To use the service, you'll need to have an Amazon Prime membership, at the cost of about $99 dollars a year.
You'll also have to pay for the equipment, including the Cloud Cam and a compatible smart lock, for about $250.
Amazon recommends you have a professional install the system, or do it yourself "if you're handy."
From there, you can program the lock to allow permitted guests inside.
The camera will record who arrives, allowing you to look at the video later.
Once Amazon verifies the person is allowed to be at your home, they'll unlock the door.
They'll lock it again when the guest leaves.
For some people, it's a natural progression of technology and security. For others, it's a scarier proposition.
"Now we're breaking down the gate, the gate, the entrance way to your home, and we're actually going into that safe zone that we really protect," Timothy Dimoff said, he specializes in security.
However, Dimoff said he's hopeful for a few reasons, including the Cloud Cam Amazon uses with the system.
"I think the fact that they're monitoring it with a camera, that's the whole difference. If they were doing this without that camera monitoring, then I would tell you this is a very unsafe direction to go," he said.
Dimoff said there are questions surrounding how secure Key will really be, including the way the system locks the door when invited guests leave, potentially leaving the door wide open for unwanted intruders.
"Do they really make sure that door is locked, so that someone else can't come in later and they can justify, say, 'oh we thought it was locked?'" Dimoff said.
However, Amazon said the service isn't for everyone, including people with pets who may run out the door at the sight of a stranger. The site recommends those with skittish animals not enroll in Amazon Key.
Even with those questions, Dimoff predicts success for Key, and he thinks we'll see more of these innovations from Amazon competitors.
"This is gonna take off," Dimoff said. "There's too big of an audience out there, too big of a customer base, coast to coast in this country, and other countries. This is going to grow exponentially."