Alarm24 is a privately owned company catering to clients in O'Fallon. It offers the installation of security systems in residential, industrial, and commercial properties—including burglar alarm monitors, fire and smoke alarms, and carbon monoxide leak detectors. The company also positions surveillance cameras and designs an access control system to restrict the entry of unauthorized individuals. Additionally, it monitors environmental, water, and temperature sensors. Alarm24 is a member of the Nation Fire Protection Association and the National Burglar and Fire Alarm Association.