PagerDuty - Cloud based monitoring service
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
VictorOps - We make on-call suck less & help teams to solve problems faster.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
xMatters - xMatters transforms event data into intelligent communication IT teams, avoiding outages and disruptions
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.