RIO DE JANEIRO // Brazilians were outraged when they learned their country was a top target of the US National Security Agency's overseas spying operation, with data from billions of calls and emails swept up in Washington's top secret surveillance programme.
Yet when it comes to the cloak-and-dagger effort of catching philandering lovers, all high-tech weapons appear to be fair game - at least to the tens of thousands of Brazilians who downloaded Boyfriend Tracker to their smartphones before the software was removed from the Google Play app store last week, apparently in response to complaints about privacy abuses and its potential to be used for extortion or even stalking.
"Brazilians are a jealous people, what can I say? Of course it's going to be popular," said Marcia Almeida, a 47-year-old woman in Rio de Janeiro whose marriage ended seven years ago in large part because of what she said was her husband's infidelity.
"It's a different type of spying," she said of comparisons to the NSA surveillance programme. "You're checking up on somebody you know intimately, not some stranger."
Functions include sending the person doing the tracking updates on their partner's location and forwarding duplicates of text message traffic from the targeted phone. There is even a command that allows a user to force the target phone to silently call their own, like a pocket dial, so they can listen in on what the person is saying.
Similar apps are marketed for smartphone users in other countries, including Europe and the United States, but Boyfriend Tracker is the first that has made any impact in Brazil, a country still irate as it learns more about Washington's snooping. Brazil has sent a government delegation to meet with US leaders about the spy programme that was revealed by Edward Snowden, the former NSA contractor who has been on the run since May.
A Google spokeswoman, Gina Johnson, said that the company does not comment on why apps are removed.
Critics have said that apps like Boyfriend Tracker could be used for more sinister purposes, like stalking. Some in Brazil argued it breaks a law against online harassment and hacking in place since April. The law is named after the Brazilian actress, Carolina Dieckmann, who had nude photos of herself leaked by hackers in 2012 after she refused to pay about Dh18,400.
However, similar apps popular on Google Play market themselves to parents as a means of monitoring how teenage children use the phone and where they are at any given moment.
Matheus Grijo, a 24-year-old Sao Paulo-based developer behind Boyfriend Tracker, said it had attracted about 50,000 users since its launch about two months ago, most since the site began attracting media attention two weeks ago.
Mr Grijo insisted his lawyer vetted the app and determined it did not violate any Brazilian laws. It is still available by direct download from his company's website.
A disclaimer on that website stipulates the app is for "social and recreational use" and absolves the developer of responsibility for any misuse. The first line of the download instructions says a woman installing the tracker on her boyfriend's phone should do so "with his consent".
