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The industry standard in open-source IT monitoring tools for servers, networks, applications, and services.

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Reviews onG2CapterraSourceForge
192 reviews tracked

The Bottom Line

Entry price

Free plan available, paid tiers above

Biggest pro

Legacy monitoring standard

Biggest con

UI very dated

TL;DR - Nagios

  • Open-source IT monitoring for servers, networks, applications, and services.
  • Offers both a free, community-supported core and an enterprise-grade paid version (Nagios XI).
  • Highly extensible with a vast plugin architecture and strong community support.
Pricing: Free plan available
Best for: Growing teams
4.6/5 across review platforms

What is Nagios?

Editorial review
Nagios offers powerful, open-source IT infrastructure monitoring solutions. Nagios Core is a free, community-supported monitoring engine that allows users to monitor websites, servers, switches, routers, firewalls, ports, applications, and metrics. It's highly extensible with a vast plugin architecture and is trusted by thousands of organizations worldwide. For users needing more advanced features, Nagios XI provides a complete IT infrastructure monitoring tool powered by the Nagios Core engine. It includes pre-installed plugins and agents, easy-to-use monitoring wizards, and powerful dashboards and reports. Nagios is designed for IT professionals and organizations looking to prevent downtime and ensure the smooth operation of their critical business processes by providing comprehensive visibility into their IT environment. The platform emphasizes community support, with thousands of plugins and add-ons available through Nagios Exchange, and offers resources like forums, documentation, and training. Nagios also provides Nagios Core Services Platform (CSP), a comprehensive package that includes essential open-source projects and a pre-configured Nagios XI VM for a unified monitoring experience.

Pros & Cons

Pros

  • Legacy monitoring standard
  • Highly customizable
  • Large plugin library
  • Free and open source
  • Battle-tested

Cons

  • UI very dated
  • Configuration complex
  • Scaling difficult
  • Setup time-consuming
  • Alternatives more modern

Ratings Across the Web

4.6(192 reviews)

Ratings aggregated from independent review platforms. Learn more

Key Features

Infrastructure monitoringAlert notificationsPlugin architectureNetwork analysisLog monitoringOpen source

Pricing Plans

Free Trial

Core (Free)

Free

  • Open source
  • Community support
  • Unlimited hosts

XI Standard

$1,995/one-time

  • 7 Nodes or 100 Services
  • Advanced Reporting
  • Custom Dashboards
  • Configuration Wizards

XI Professional

$3,495/one-time

  • Audit Logging
  • Bulk-Modification Tools
  • Capacity Planning
  • Automated Host Decommissioning

Reviews

4.6/5

Across 192 verified user reviews on G2, SourceForge, Capterra

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Nagios FAQ

What is Nagios?

Nagios is the industry-standard open source IT monitoring tool that tracks servers, networks, applications, and infrastructure. With 25+ years of monitoring expertise and 1 million+ users worldwide, it helps prevent downtime before it impacts business operations.

Is Nagios free?

Yes, Nagios Core is completely free and community-supported. For users needing additional features like pre-installed plugins, monitoring wizards, dashboards, and reports, Nagios XI is available as a paid enterprise alternative.

What can Nagios monitor?

Nagios provides complete infrastructure monitoring for Windows, Linux, networks, and services. It includes 50+ ready-made plugins and supports thousands of community-built add-ons through its powerful plugin architecture.

Who should use Nagios?

Nagios is ideal for organizations seeking free, powerful monitoring capabilities, teams managing complex infrastructure, users preferring open-source solutions, and companies needing extensive customization through plugins.

Source: nagios.org

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