The online grocery delivery business seems to get more crowded - and more competitive - by the minute. Tech giants Google and Amazon.com are offering it in some major cities, and so are upstarts such as Instacart, Postmates and FreshDirect. These newcomers are battling with more established businesses such as Peapod, which has been delivering groceries for more than 20 years, and services from companies such as Wal-Mart that allow customers to place orders online and pick them up at a nearby store.

Amazon reportedly will open a brick-and-mortar shop in Midtown Manhattan in time for the holiday shopping season and that it will be a place for customers to return products, make exchanges or pick up their online orders.