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 with our status page aggregator. IT teams choose IsDown to monitor all their vendors and get alerts whenever an outage occurs. Integration with Datadog, PagerDuty, Slack, Microsoft Teams, and a lot more.