PagerDuty - Cloud based monitoring service
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.
One Call Now - One Call Now's message notification delivers automated phone calls, SMS text messages and emails within moments to any group.
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.
OpsGenie - Alerting and On-Call Management for Dev&Ops Teams
RedGate SQL Monitor - SQL Monitor helps you and your team find issues – before they become problems