PagerDuty - Cloud based monitoring service
Freshservice - Freshservice: the one-stop cloud solution for all your IT management needs.
OpsGenie - Alerting and On-Call Management for Dev&Ops Teams
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
Squadcast - Automate incident response, reduce downtime and enhance your tech teams’ delivery with a unified platform.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.