Nagios is a recursive acronym: "Nagios Ain't Gonna Insist On Sainthood"[4] – "sainthood" makes reference to the original name NetSaint, which changed in response to a legal challenge by owners of a similar trademark.

[5] "Agios" (or "hagios") also transliterates the Greek word άγιος, which means "saint".

[8] The community team members who were replaced continued their work under the name Monitoring Plugins along with a different website with the new domain of monitoring-plugins.org.

While the front-end of Nagios Core is mainly CGI with some PHP,[14] most of the Nagios XI front-end and back-end are written in PHP including the subsystem, event handlers, and notifications, and Python is used to create capacity planning reports and other reports.

RRDtool and Highcharts are included to create customizable graphs that can be displayed in dashboards.