Zabbix - Track, record, alert and visualize performance and availability of IT resources
Wren - Offset your carbon footprint by saving rainforests
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.
Website Carbon Calculator - Find out the how much CO2 your website emits
Prometheus - An open-source systems monitoring and alerting toolkit.
Trip to Carbon - A carbon footprint calculation API for travel.