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.
Freshping + Freshstatus Integration - Create incidents instantly when Freshping reports downtime
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Sorry App - Turn outages into opportunities
Better Uptime - We call you when your website goes down
Freshworks - Delight your customers, from wherever you are