Citizen
Last October, a new app appeared on the App Store aimed at preventing crime.
Called Vigilante, the app showed users where crime was happening in real time - and seemingly encouraged them to help stop it.
Vigilante went viral in less than two days, spreading quickly due to a controversial video that showed someone using the app to prevent a would-be mugging, filming the incident and scaring the assailant away.
But Vigilante had a short life span: The app was pulled from the App Store about 48 hours after it launched due to safety concerns.
Now, Vigilante is back on the App Store as Citizen, a crime avoidance tool for metropolitan areas. Here's how it works.