Nagios

Nagios is the industry standard in open source IT infrastructure monitoring, trusted by over 1 million users worldwide with 25-plus years of production experience and 250,000-plus annual downloads. The platform provides powerful monitoring and alerting for servers, networks, applications, and services, enabling organizations to detect and resolve problems before they impact critical business processes. Nagios Core is the free open source monitoring engine that started the project, supporting monitoring of websites, servers, switches, routers, firewalls, ports, applications, and custom metrics through a plugin architecture with over 5,000 community-built add-ons available on the Nagios Exchange marketplace. NCPA is the official cross-platform agent that monitors Windows, Linux, and macOS systems in real time with built-in checks for CPU, memory, disk, network, and process metrics. The Nagios Plugins package includes 50-plus ready-made checks such as check ping, check ssh, check http, check disk, and check load. Nagios Mod-Gearman adds distributed worker scalability for monitoring large environments with thousands of hosts. Configuration tools provide web interfaces, auto-discovery scripts, and change management to simplify setup without manual file editing. Visualization add-ons transform monitoring data into dashboards, network maps, and performance graphs. Nagios XI is the commercial enterprise edition with advanced dashboards, reporting, and multi-tenancy. The annual Nagios World Conference 2026 is scheduled for September 14-17 in St. Paul, Minnesota.