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.
Callmama - Get cheap international calling, international virtual number, Call Mama Gives an added advantage to send message and make calls to non-user of Callmama App.
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.
CallHippo - Easy to use Phone System with World-Class Support
Zabbix - Track, record, alert and visualize performance and availability of IT resources
KrispCall - Virtual cloud phone system for business