Zabbix - Track, record, alert and visualize performance and availability of IT resources
x.ai - x.ai is a tool to schedule meetings for you and your team.
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.
CozyCal - Online appointment scheduling
Prometheus - An open-source systems monitoring and alerting toolkit.
Meekan - Connecting the world's calendars