Citizen is a mobile app that sends users location-based safety alerts in real time. It allows users to read updates about ongoing reports, broadcast live video, and leave comments. The app uses radio antennas installed in major cities to monitor 911 communications, with employees filtering the audio to generate alerts. The app is currently available for iOS and Android devices in New York City, the San Francisco Bay Area, Baltimore, Los Angeles, Philadelphia. Detroit, Indianapolis, Phoenix, Cincinnati, and Cleveland.
,Developed by sp0n, Inc. and originally called Vigilante in 2016, it was rebranded and launched in New York on March 8, 2017. On July 15, 2019, Forbes reported that Citizen had over a million active users. Investors include Sequoia Capital, 8VC, RRE Ventures, Slow Ventures, and Lux Capital.