Obzrv.it - Obzrv.it is a universal web monitoring service.
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.
WebARX - Website Protection, Managed Website Security & Website Monitoring
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Visualping - Visualping is the easiest to use website checker, webpage change monitoring, website change detector and website change alert software of the web. Read more about Visualping.
Better Uptime - We call you when your website goes down