WebGazer is an uptime monitoring platform that checks if your website is up as it should be and notifies you if anything goes wrong
UptimeRobot - Free Website Uptime Monitoring
LightStep - We deliver insights that put organizations back in control of their complex software apps.
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.
PingPing - A simple tool to monitor your website and SSL
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Rootly - Rootly helps build a consistent incident response process by automating manual admin work like creating incident channels, Jira tickets, Zoom rooms, and generating postmortem timelines, all from within Slack.