Zabbix vs Checkmk: What are the differences?
What is Zabbix? Track, record, alert and visualize performance and availability of IT resources. Zabbix is a mature and effortless enterprise-class open source monitoring solution for network monitoring and application monitoring of millions of metrics.
What is Checkmk? A tool for Infrastructure & Application Monitoring. It is a software developed for IT Infrastructure monitoring. It is used for the monitoring of servers, applications, networks, cloud infrastructures, containers, storage, databases and environment sensors.
Zabbix and Checkmk belong to "Monitoring Tools" category of the tech stack.
Zabbix is an open source tool with 599 GitHub stars and 208 GitHub forks. Here's a link to Zabbix's open source repository on GitHub.