The social network Foursquare has become so popular in the tech community that it now has more than a million users.
"I like to use it to keep track of where everyone is," said Foursquare user Laura Glascott.
"Absolutely the best way to figure out where all of my friends were," said Foursquare user Micah Saul.
That's great if you have "BFFs," but what do you do to avoid running into an ex or someone who is no longer a friend? Enter San Francisco computer technician Jesper Andersen, creator of Avoidr. It tells Foursqaure users where they should not go. It is part of what he calls "de-friending."
He created it after some friendships went sour and he was on Foursquare.
"I started to check it religiously to see where am I not going to go and I felt like I was being a stalker, which is really unhealthy, right? So I was thinking maybe you could build a website that would make it more emotionally correct," said Anderson.
So how does it play with Foursquare users?
"If I could set it to avoid them, someone that I've been really missing on purpose, sure, I'd use it," said Foursquare user John Paul.
Saul says he has used it.
"OK, if all of them are at that place, maybe I don't so much want to be there," he said.
"Were I to suddenly do something to alienate myself from my group of friends, that might be something I would like to leverage," said Glascott, although she thinks it sounds anti-social.
"I think a lot of people view it as an anti-Foursquare tool," said Anderson. "I think it's more of a filter."
Currently Avoidr is just a website, but Andersen thinks he should have it up as an app in about two weeks.