PagerDuty - Cloud based monitoring service
ServerSuit - ServerSuit is a browser based program that enables remote Linux administration, monitoring, website hosting, and server setup automation.
OpsGenie - Alerting and On-Call Management for Dev&Ops Teams
Netumo - Ensure healthy website performance, uptime, and free from vulnerabilities. Automatic checks for SSL Certificates, domains and monitor issues with your websites all from one console and get instant notifications on any issues.
Zenduty - Zenduty is a state of the art incident management solution that provides cross-channel alerts to your team whenever critical incidents occur.
AppZero - AppZero is a monitoring and migration tool that allows users to keep track of different applications and servers in both simple and complex IT environments.