One Call Now - One Call Now's message notification delivers automated phone calls, SMS text messages and emails within moments to any group.
HackerOne - HackerOne provides a platform designed to streamline vulnerability coordination and bug bounty program by enlisting hackers.
Notifuse - A 1-to-many notification API that's simple to use
Intruder - Intruder is a security monitoring platform for internet-facing systems.
OnPage - OnPage critical alert and incident management system enables rapid resolution of critical IT, healthcare or IoT incidents through efficient communication.
Nessus - Nessus Professional is a security platform designed for businesses who want to protect the security of themselves, their clients, and their customers.