Police departments in Dallas, San Jose, and Orlando have started to use Nextdoor's Virtual Neighborhood Watch to communicate with homeowners. Denver and San Francisco will begin to use the service soon.
In Dallas, the company says 243 neighborhoods are using Nextdoor, the police have trained 300 neighbor police officers and they have mapped local police stations to the Nextdoor communities. The departments even post surveillance videos.
Tolia said that once a week the Silicon Valley-based company hears about a crime being stopped because of communication that went on over the service. Police departments and the community lead can inform neighbors of high-priority alerts or news via text message.
But while Nextdoor has begun to fight crime, its hard not to imagine the crimes that could be started by users of the site. The site requires people to input their real name and addresses; that's how people will see them on the service and on neighboorhood maps. In the Internet age, that's something you think twice about before typing in on a social network.
Tolia assured ABC News that nothing on Nextdoor can be indexed by Google and you have to be logged into that specific neighborhood to see anything about users. For instance, if you live in a town near New York City, only people in that town can see you. There is also the option to leave out your numeric house address; you can just put in your street. In addition, Nextdoor has integrated 50 different sex offender databases. People listed on them won't be able to join.
"Privacy is a benefit, not a risk for users," Tolia said. He said 30 percent of the users list their children's names and ages.
Riggs said privacy and personal safety was actually something he had never thought about when using the service. Instead, he sees the service as being a safety shield. "People are able to freely communicate," he said. "And the communication regarding something they see that's security or safety related has been extremely effective."