GRUB - Multiboot boot loader
Zabbix - Track, record, alert and visualize performance and availability of IT resources
EasyBCD - EasyBCD is NeoSmart Technologies multiple award-winning answer to tweaking Windows bootloader.
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.
EasyUEFI - Manage EFI/UEFI Boot Options & Manage EFI System Partitions & Fix EFI/UEFI Boot Issues
Prometheus - An open-source systems monitoring and alerting toolkit.