Blumira - Blumira's threat detection platform offers both automated threat detection and response, enabling organizations of any size to more efficiently defend against cybersecurity threats in near real-time.
Server Monitoring - A server monitor is a tool that monitors your server and website on close intervals and reports to you if it's inaccessible.
Google StackDriver - Stackdriver provides monitoring services for cloud-powered applications.
NIXStats - SaaS monitoring tool for window/linux servers and websites. Think up-time robot but with more features.
Devo - Devo delivers real-time operational & business value from analytics on streaming and historical data to operations.
mackerel.io - mackerel.io is a server and application performance monitoring platform.