Amazon service will let couriers open front doors
Amazon is launching a service that will let couriers open people's front doors and put deliveries inside.
Users of Amazon Key will need a smart lock and Cloud Cam camera.
Couriers will scan a package barcode and once the delivery has been verified online, the camera will start recording and the delivery person will be able to unlock the door using an app.
One analyst said consumers would have to be convinced the system was secure if they were to use it.
Users will be able to choose to watch the delivery live or receive a short video after the drop-off.
Compatible smart locks include models made by Yale and Kwikset.
The system can also be used to give access to dog walkers, cleaners or visiting guests.
The online shopping giant has long sought ways of improving delivery convenience for customers - including a trial with Audi in 2015 in which packages were deposited in car boots.
"Amazon seems to be on an unstoppable mission to own every aspect of the home," said CCS Insight analyst Ben Wood.
Mr Wood said he used a video doorbell and smart lock to give couriers access to his garage. He said asking customers to make their front doors accessible might be more difficult.
"My understanding is there's an awful lot of work being done to make connected locks secure," he said, in order to address security concerns.
"But it would only take a few incidents to stop this dead in the water - people wouldn't want to have something on their front door if they felt it wasn't secure."
Last month, Amazon rival Nest launched new smart home products, including an internet-connected intruder alarm and a video-streaming doorbell that could be paired with a Yale smart lock.
This too allows doors to be unlocked remotely, giving access to friends or couriers.
Amazon Key will initially be available in 37 US cities where the firm's own courier, Amazon Logistics, will handle deliveries.
"These individuals are thoroughly vetted, with comprehensive background checks and motor vehicle records reviews," Amazon says.
Users with home security systems will need to disarm them on delivery day in order to allow couriers access.
Amazon also recommends not using in-home delivery if a pet can reach the front door.
The Amazon-made Cloud Cam camera costs $120 (£90) and a bundle with a smart lock and free installation will be available for $249.99.