ShopAdvisor spent its first two years searching for a promising value proposition. It raised $11 million in venture financing but was still in search of what Mr. Cooper called “the breakout business model.” The advent of beacon technology this year solidified the mission. “That last leg on the stool has really exploded the business,” he said.

For example, when Elle, the popular women’s magazine, began planning for its 30th anniversary this year, the publication decided it had to do something noteworthy in addition to its celebratory September fashion and beauty issue. The 668-page issue, the largest in Elle’s history, would be flush with special content to support its many advertisers but “we felt it was incumbent upon us to do something innovative,” said Kevin O’Malley, Elle’s senior vice president and publisher.

Image ShopAdvisor incorporates data analytics that filter a shopper’s preferences and provide a way for retailers to send personalized alerts to consumers who have downloaded a brand’s app. Credit... ShopAdvisor

Elle connected with ShopAdvisor and in August they started a pilot program called Shop Now. As part of the Shop Now campaign, Elle formed partnerships with such advertisers as Guess, Levi’s and Vince Camuto, and ShopAdvisor placed beacons in more than 1,600 stores around the country. Beacons, introduced in the last two years, are inexpensive, battery-powered, hockey-puck size digital sensors placed in locations to precisely identify and communicate with customers carrying smartphones.

ShopAdvisor created a mobile app using beacon and geofencing technology for Elle readers, who tend to be avid shoppers. The geofence detects that an Elle reader with the app is near, and the beacon then precisely tracks that shopper’s movements when she enters the store. It also sets off push alerts for that customer, suggesting specific items such as jeans or shoes that the customer has previously expressed interest in, along with curated content from Elle magazine. The content includes product reviews, top picks from Elle editors, coupons and other personalized marketing messages just for the customer.

“If you get a generic jeans offer from Guess, you are more likely to disregard it or delete it,” Mr. O’Malley said. “Of course Guess will tell you they are the best. But if we say those skinny, low-rise jeans in this model is one of our picks, that’s an editorial endorsement and brings third-party credibility and authority to the alert.”

According to Mr. O’Malley, previous location-based marketing resulted in less than 1 percent of smartphone users entering stores, a disappointing result. After six weeks of the Shop Now campaign, more than 8 percent of those who received the app visited the stores, an increase retailers consider highly significant. Elle plans to start the next phase of the program in early 2016.