Walmart will now deliver groceries right to your fridge for a $20 monthly fee

Walmart today is officially joining the niche trend of delivering goods inside people's homes.

The Walmart InHome grocery service launched Tuesday in Kansas City, Pittsburgh and Vero Beach, Florida, letting customers in those three cities order fruit, milk and other perishable items right to their fridges. The service is available for refrigerators in either homes or garages.

The new service, which Walmart previously said would be coming in the fall, will cost $20 a month (plus the cost of groceries), with the first month free. A $50 smart lock device will also be needed, though expert installation is included at no additional cost.

In-home deliveries are a small but growing part of online shopping, with companies offering the service to help cut down on porch thefts and rain-soaked cardboard boxes. Plus, in-home deliveries could help broaden the kinds of items people are willing to buy online, such as fish, jewelry or bulky furniture, which wouldn't do well sitting for hours on a front stoop. Similar efforts include Key by Amazon and Latch, which focus on package deliveries for homes and apartments, respectively.

Walmart's grocery service may also encourage people to buy more food online, since they won't have to wait at home to accept the order. That work could help Walmart, the largest grocer in the US, fight off plenty of online delivery competitors, including Peapod, Amazon and Fresh Direct. Walmart also bolstered its grocery delivery work with its Delivery Unlimited membership program, which it's expanding to 1,400 stores in the US.

Walmart said it's working with Level Home to provide front door smart locks and Nortek Security & Control for garage door access.