Zabbix - Track, record, alert and visualize performance and availability of IT resources
HackerOne - HackerOne provides a platform designed to streamline vulnerability coordination and bug bounty program by enlisting hackers.
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Intruder - Intruder is a security monitoring platform for internet-facing systems.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
Forcepoint Web Security Suite - Internet Security