Terms of the deal were not disclosed, but the motivation is clear: Consumers are relying more on their smartphones for shopping whether they shop online or in brick-and-mortar stores.

Ann Taylor, Crocs, and Leading Hotels of the World use Mobify’s software, which runs on Amazon (AMZN) Web Services, to optimize content for viewing and interacting with mobile devices. Chicago-based Dónde, will help Mobify customers serve up targeted discounts or ads to shoppers, or even just passersby, based on their proximity to a store, or on their location within the store itself.

“A lot of companies still think of a mobile device or phone as just a smaller screen but it is much more than that. It’s an appendage for people. Their mobile is with them all the time, and that’s a different dynamic than having to get to a laptop to do something,” Cliff Conneighton, chief marketing officer for Vancouver, B.C.-based Mobify, told Fortune.

Mobify competes with companies like Branding Brand and MoovWeb while Dónde squares off with parts of the Adobe Marketing Cloud (ADBE) and Brandify (formerly known as Where2GetIt.) But online shopping is a focus of companies from Demandware (DWRE) to Oracle (ORCL), which built its commerce platform atop its 2010 acquisition of Art Technology Group or ATG. IBM(IBM) is also in the mix thanks to acquisitions of companies including Unica and Silverpop.

Mobify’s thinking is that combining Dónde’s location smarts with a slick mobile-friendly interface will mean better engagement with prospective customers and thus better sales. Mobify, for instance, supports Google (GOOG) Chrome’s push technology that sends consumers alerts about specials going on at nearby merchants as they walk by. If they then enter the store, they may get another notification, or coupon, to entice them to buy even more.

The challenge is to be proactive and to get customers to choose the kinds of discounts and information they want to receive. It also involves looking at the past online behavior of shoppers—as long as they opt into it.

Like many other e-commerce acquisitions, the Mobify-Dónde combo is aimed at reducing retailers’ reliance on “spray and pray” marketing. Instead, retailers can, in theory, focus on just the shoppers who are more likely to buy something.

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