Icinga 2
Icinga 2 is a general-purpose monitoring application and the next generation after Icinga 1.x - which was a Nagios fork. It should fit the needs of a small environment as well as big installations.
Rewritten from scratch in C++, with multi-threading and cluster support.
Features:
* All common features of Icinga and Nagios
* Much faster and more scalable than Icinga 1 and Nagios
* New configuration format, more intuitive and template based
* Monitoring several services by executing checks (see nagios-plugins*)
for example ICMP/ping, SMTP, POP3, HTTP, NNTP, or other TCP port
* Any small script can be used as a check plugin, when following the Nagios
plugin API
* Notifications about alerts with any custom script, or shipped examples
* Native support for Livestatus and Graphite