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.
OwnedByFAANG - A simple list of who and what is OwnedByFAANG.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Mozilla Facebook Container - Take control of all your Facebook data
Better Uptime - We call you when your website goes down
Site24x7 - Site24x7 offers both free & paid website monitoring services. Monitor websites remotely and receive instant email/sms alerts if your website becomes unavailable. View uptime & performance graphs of your website monitors.