PagerDuty - Cloud based monitoring service
UptimeRobot - Free Website Uptime Monitoring
OpsGenie - Alerting and On-Call Management for Dev&Ops Teams
StatusPage.io - StatusPage.io is the best way for web infrastructure, developer API, and SaaS companies to get set up with their very own status page in minutes. Integrate public metrics and allow your customers to subscribe to be updated automatically.
Squadcast - Automate incident response, reduce downtime and enhance your tech teams’ delivery with a unified platform.
FreshStatus - Better status pages in 1-click, FREE FOREVER