Statsignal - Statsignal is a simple and cost-effective way to monitor your website or server and publish a status page of your system.
OnlineOrNot - Uptime monitoring for software teams (even teams of one).
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
HetrixTools - FREE Uptime Monitoring + Server Monitoring + Status Page + Blacklist Monitoring!
Uptime Kuma - A fancy self-hosted monitoring tool.
StatusPage.io - StatusPage.io is the best way for web infrastructure, developer API, and SaaS companies to get set up with their very own status page in minutes. Integrate public metrics and allow your customers to subscribe to be updated automatically.