It isn't just the NSA we have to worry about snooping on our cellphones now: several new start-ups are sneaking software into apps that builds individualized profiles of users' spending, browsing, and travel habits, then sells the info to advertisers. The new tech is way more advanced than old-fashioned browser cookies, reports the New York Times—it can identify the desktop computers, laptops, tablets, and other devices you own, even if they're in no way connected to your phone. "We’re observing your behaviors and connecting your profile to mobile devices," says the COO of Drawbridge, which tracks 1.5 billion devices.
Drawbridge, one of several similar new companies, watches what you do on your phone, then uses behavioral patterns and statistical modeling to determine all the other devices you use. It then assigns you an anonymous identifier so advertisers can market to you on all of your screens. The Times uses the example of searching for a Hawaiian vacation on your work computer, then receiving an ad for airline tickets to Hawaii later on your smartphone. The company says its software is so accurate, it can even identify—and market to—different users on a shared tablet. "In the old days of ad targeting, we give them a list of sites and we'd say, 'Women 25 to 45,'" says one online retailer. "In the new age, we basically say, 'Go get us users.'" (Read more online advertising stories.)