Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.
DCImanager - DCImanager is a platform for managing physical equipment. Connect any physical equipment to a single platform. Use the platform to manage your servers, switches, PDU as well as physical and virtual networks.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Atlassian Data Center - Deploy Atlassian's software in your own data center with clustered failover and more to support large and mission critical deployments.
Better Uptime - We call you when your website goes down
Device42 - Automatically maintain an up-to-date inventory of your physical, virtual, and cloud servers and containers, network components, software/services/applications, and their inter-relationships and inter-dependencies.