WebGazer is an uptime monitoring platform that checks if your website is up as it should be and notifies you if anything goes wrong
StatusGator - Monitor all your hosted applications, vendors, and websites, and keep your team informed of outages. StatusGator is the world's premier status aggregator, status page, and website monitoring tool.
UptimeRobot - Free Website Uptime Monitoring
stts - St. Teresa of Avila Catholic School is a Pre-K through 8th grade school educating children for over 55 years in the Catholic Tradition.
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.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
IsDown App - Monitor all your cloud services status pages in one place