While most social networks aim to connect people, one new service seeks to join the growing trend of doing the opposite and help you avoid them.
Cloak uses public location data from other social networks, Foursquare and Instagram, to determine the locations of others you know.
Users can choose to receive an alert when certain people are believed to be nearby.
It is the latest in the recent trend of "anti-social", or secretive, apps.
Apps such as Snapchat - which deletes photographs and videos seconds after they have been viewed - and Secret - which broadcasts messages anonymously - are growing in popularity.
Likewise WhatsApp, a private-messaging service recently bought by Facebook for $19bn (£11.4bn), indicates a shift back to conducting online conversations in private.
Cloak describes itself as a method to "avoid exes, co-workers, that guy who likes to stop and chat - anyone you'd rather not run into".
It was created by programmer Brian Moore and the former creative director of viral news site Buzzfeed, Chris Baker.
Mr Baker told the Washington Post that his service was typical of the direction social networking was taking.
"Personally, I think we've seen the crest of the big social network," he said.
"Things like Twitter and Facebook are packed elevators where we're all crammed in together… I think anti-social stuff is on the rise. You'll be seeing more and more of these types of projects."
Nick Jones, editor-in-chief of App Magazine, told the BBC he was unconvinced - though tempted.
"It does sound like a gimmick," he said. "But I might use it myself!"
He suggested that these niche apps were being developed not because of any great consumer need, but because developers are keen to corner some of the few remaining untapped social-media markets.
"People are having to diversify their apps and find some unique angle to their app, and then try and sell it to Facebook and make a pretty penny."
However, he admitted: "Secrecy has its advantages for people. It's quite attractive."
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