LambStatus - Serverless status page system which enables you to build a status page with minimum effort and cost!
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.
cState - 🔥 Free & open source under MIT!
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Fyipe - Status page, monitoring and on-call made simple.
Better Uptime - We call you when your website goes down