Automotive parts and accessories retailers get roughly 60% of site traffic from mobile devices, the highest among all retail categories tracked by Internet Retailer. The high mobile traffic may be because shoppers are comparison shopping while they're in a store or auto shop. On the other hand, office supplies retailers get the least share from mobile devices at 27%. This may be because consumers don't browse around as much for office supplies, and because they purchase these products when it's top-of-mind, such as back-to-school season or when they're in their offices (near a desktop).

Of the 14 retail apps consumers say they have downloaded on their phones, six are retailers that operate marketplaces, according to an Internet Retailer/Bizrate Insights survey. The same survey was conducted in 2017, and here's how online shopper habits changed year over year.