Zabbix - Track, record, alert and visualize performance and availability of IT resources
Veeam Backup - Backup and restore VMware and Hyper-V virtual machines with Veeam Backup Free Edition. Unlimited hosts and VMs. Free forever.
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Rubrik - Rubrik delivers instant application availability for recovery, search, cloud, and development.
Prometheus - An open-source systems monitoring and alerting toolkit.
Zerto - Virtual replication & recovery solution