Shopular is popular: Since launching out of the renowned Silicon Valley business accelerator Y Combinator a year and a half ago, the mobile couponing app has been downloaded more than 3 million times, with 1.5 million coupons redemptions each month, according to CEO and co-founder Navneet Loiwal. Over the last quarter, the average amount of time a consumer spends with the app has doubled, he adds, and with more than 30,000 reviews it has consistently rated between 4.8 and 5.0 out of five stars in Apple Inc. and Google Inc. app marketplaces. Its users are evenly divided between Android and iPhone versions.

When a shopper downloads the app, she is prompted to select her favorites from the participating 200 U.S. retailers. The average shopper choses 30 retail brands, Loiwal says. Then, using geolocation on her smartphone, the app notifies her of any deals from her preferred retailers when she walks into one of their store locations or the entrance of a shopping mall that houses a store. The shopper may also use the app to browse current deals and digital circulars from anywhere.

Although Shopular says leading consumers into bricks-and-mortar stores is the focus of its model, consumers can redeem select coupons on the e-commerce site of participating retailers.

Shopular also includes social features, allowing consumers to comment on deals within the app, with their remarks appearing below the mobile coupon. “70% of our deals get commented on, meaning that our community loves to talk about deals, share tips and tricks about deals and exchange shopping banter right in the app,” Loiwal says. In response, Shopular plans to add more community sharing features this year, he says, without giving details.

The company also plans to enhance its personalization capabilities for offers and notifications, he says. And as it increases the number of retailers distributing mobile coupons through the app, it will expand into new retail categories, including grocery, he says.

So far, Shopular has only been testing the service with retailers, Loiwal says, and is not releasing results. It charges a fee for each coupon impression or redemption, depending on a retailer’s goals, he says. “We are conducting trials and building alliances with marquee retailers who are essential revenue generation partners for us,” he says. Those retailers include Gap Inc., No. 19 in the 2014 Internet Retailer Top 500 Guide; The Home Depot Inc., No. 16; Kohl’s Corp., No. 23; Macy’s Inc., No. 8, and J. Crew Group Inc., No. 60.