Nagios XI is the commercial monitoring product built on the open-source Nagios Core engine, licensed perpetually per node; pages here cover moving to Nagios Core, Icinga, Checkmk or Zabbix.
For Nagios XI customers weighing renewal against the free engine underneath it: what Nagios Core keeps (checks, plugins, notifications) and loses (wizards, dashboards, reporting, REST API, support), and the configuration and staffing work that replaces them.
Comparing node-licensed Nagios XI with free Zabbix: templates and discovery against Nagios plugins and wizards, the database-backed history Zabbix keeps, distributed monitoring with proxies, and the effort of switching models.
Checkmk Community still runs on the Nagios core. This page compares Nagios XI with Checkmk's rule-based configuration and auto-discovery, the Checkmk Micro Core in the commercial editions, and edition pricing against XI node tiers.
Icinga started as a Nagios fork and keeps Nagios plugin compatibility. This page compares Nagios XI with Icinga 2, Icinga Web and the Director for configuration, high-availability masters and satellites, and Icinga's subscriptions for packages and support.
Moving from Nagios XI to Icinga 2: reusing Nagios plugins, converting host and service definitions to Icinga DSL apply rules, importing objects with the Director, rebuilding dashboards and reports, and setting up distributed zones.
Moving Nagios XI hosts and checks to Checkmk: re-running service discovery instead of copying service definitions, keeping legacy Nagios plugins as active checks where needed, rebuilding notifications and choosing Community or a commercial edition.
Cost of ownership by component: Nagios XI perpetual licenses by node, the Enterprise add-on and annual maintenance renewals, against Icinga or Checkmk subscriptions or free editions, servers, migration effort and ongoing administration.
Tell us what you're working on, whether it's a deployment, an audit, a security test or a cyber range. You'll speak with an engineer who can help you scope it.