Have you ever seen a fleet of police cars barreling down the street, sirens blaring and lights ablaze, and wondered, "huh, I wonder what happened?" As a university student living in Chicago, this is a pretty common occurance. However, I was only ever informed about crimes in the city if they happened on my campus. With no knowledge of police scanners and no time to watch the nightly news, many people within my demographic have limited knowledge of the dangerous events taking place in their city.

Enter Citizen, an app that displays ongoing crimes in your city on a map, similar to how the Uber app shows drivers nearby. Your location is marked by a blue dot, while red and yellow dots mark trending or recent incidents. The app was relaunched in March after battling against App Store restrictions and some rebranding. Currently, the app is only available in New York City, Los Angeles, Philadelphia, Baltimore, and most recently, the San Fransisco Bay Area. The app seems to be for anyone concerned about their safety in a metropolitan area. Popular among millennials and university students, Citizen issues constant alerts about nearby crimes or accidents.

Citizen, which is based out of New York City, has a staff of about seventy employers who utilize police, EMT, and firefighter scanners to record incidents and upload them onto the map. The app also features a live-streaming service, in which residents can react to and upload footage of the incident as it unfolds. This led to controversy in the past, as many people felt as if the app encouraged ill-trained individuals to involve themselves in crime.

Coincidentally, Citizen actually started out as an app named Vigilante. Creator Andrew Frame created Vigilante to combat the "by-stander" effect, a phenomena that, according to Psychology Today, "occurs when the presence of others discourages an individual from intervening in an emergency situation." Although the name of the app has been changed, the official mission of informing the people of dangerous situations has remained the same. Citizen's website claims that by informing residents of the events in their communities, they are "empowering the city of the future."

Although Frame has officially denounced the app's early encouragement of vigilante behavior, he does believe that it's up to an informed community to partake in ending crime. So far, Citizen has been involved in discovering missing persons and rescuing kidnapped children, according to their official blog.

Citizen plans on expanding to more of America's major metropolises, letting users request cities on the official site.