PagerDuty - Cloud based monitoring service
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.
VictorOps - We make on-call suck less & help teams to solve problems faster.
AppDynamics - Get real-time insight from your apps using Application Performance Management—how they’re being used, how they’re performing, where they need help.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
xMatters - xMatters transforms event data into intelligent communication IT teams, avoiding outages and disruptions