Everbridge is a company that sells communications services for notifications of emergencies. It began operations in 2002. In an emergency, Everbridge sends messages via telephone, text message and email, but stop once they know that a person has read a message. An app allows emergency managers to track geotagged tweets that contain specific hashtags and use this information to respond to incidents as they occur. Their system was used in 2012 to send over 10 million messages to residents during Hurricane Sandy. During the Boston Marathon bombings in April 2013, the city of Boston used Everbridge for its critical communications. Everbridge relayed information to business operators, employees, firefighters, hospital staff, police and residents after the explosions and during the lockdown of Boston, Watertown, Waltham and surrounding areas. It was also used during the COVID-19 pandemic to provide updates to Boston residents.