One Call Now - One Call Now's message notification delivers automated phone calls, SMS text messages and emails within moments to any group.
PagerDuty - Cloud based monitoring service
Notifuse - A 1-to-many notification API that's simple to use
VictorOps - We make on-call suck less & help teams to solve problems faster.
OnPage - OnPage critical alert and incident management system enables rapid resolution of critical IT, healthcare or IoT incidents through efficient communication.
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.