NIXStats - SaaS monitoring tool for window/linux servers and websites. Think up-time robot but with more features.
Crisp Status Page - Monitor servers and let users know if something goes down.
OpsDash - All-in-one solution for monitoring servers, services, uptime and databases. Curated Dashboards. Rule-based alerting.
Robusta - SRE Copilot for Kubernetes
Monitornator - Server monitoring made simple
Komodor - The Kubernetes native troubleshooting platform