There is also icinga2. So how does one decide which one to use? For a mixed environment (windows, linux, etc) which monitoring tool is better when both server and client is considered?
Thanks for the information. Currently, we are using icinga + check_mk combination and mostly happy with that. However since both icinga and check_mk are going their ways, it is no longer possible to use them together. Also I want to check out some modern alternatives like the ones you suggested.