PagerDuty - Cloud based monitoring service
Dynatrace Load - Dynatrace Load lets you test the performance of web and mobile applications with the realism of load generation from the cloud.
VictorOps - We make on-call suck less & help teams to solve problems faster.
Apache JMeter - Apache JMeter™.
xMatters - xMatters transforms event data into intelligent communication IT teams, avoiding outages and disruptions
Sitespeed - Sitespeed.io is an open source tool that helps to analyze and optimize website speed and performance.