Zabbix - Track, record, alert and visualize performance and availability of IT resources
Nagios Core - Nagios Core is a fastest-growing IT Infrastructure monitoring and alerting solution that is created for all sizes of businesses.
Observium - Observium
Exoprise - Exoprise provides Digital Experience Monitoring for enterprise SaaS applications like Microsoft 365, Salesforce, ServiceNow, Active Directory, SSO, Okta, Box, and more!
Nagios - Complete monitoring and alerting for servers, switches, applications, and services
Catchpoint - Catch issues before they impact your business