Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
MJML - The open source framework for responsive emails
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.
Stripo - Stripo is an all-in-one email design platform. We enable our clients to build emails of any complexity, including interactive AMP emails, really fast and easy.
Prometheus - An open-source systems monitoring and alerting toolkit.