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Nagios

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

MonitoringDevOpsCloud & Infrastructure
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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.
how we evaluateSourcenagios.org ↗

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)

Nagios holds an aggregate rating of 4.6 out of 5 from 192 reviews across G2, Capterra and SourceForge, last checked March 18, 2026.

G288 reviews
4.4/5
Capterra44 reviews
4.5/5
SourceForge60 reviews
5/5

Ratings aggregated from independent review platforms. Learn more

Key Features

Infrastructure monitoringAlert notificationsPlugin architectureNetwork analysisLog monitoringOpen source

Pricing Plans

Free Trial

Pricing checked Aug 20, 2026

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
Calculate your costView full pricing

Is Nagios worth the price?

85/100

Nagios' pricing model, with a robust free tier and one-time purchase options for commercial versions, is quite generous compared to many subscription-based monitoring tools.

The XI Standard at $1995 offers a solid entry point for small to medium businesses, while the XI Professional at $3495 provides advanced features for larger enterprises. This model is best for organizations looking for a perpetual license rather than ongoing subscription costs.

Hidden Costs & Gotchas

Support beyond initial purchase is extra

Plugin/integration development costs

Hardware for self-hosting

Training for complex configurations

How Nagios Compares to Competitors

Compared to subscription models like Datadog, which can quickly accrue costs based on hosts and metrics, Nagios offers a one-time purchase for its commercial versions. While Datadog's infrastructure monitoring starts around $15/host/month, Nagios XI Standard at $1995 for 7 nodes provides a fixed cost that can be more economical in the long run for stable environments. Similarly, compared to Zabbix, which is entirely open-source and free, Nagios XI offers pre-built commercial features and support for those willing to pay a one-time fee.

Reviews

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4.6/5

Across 192 verified user reviews on G2, SourceForge, Capterra

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Still deciding?

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Nagios FAQ

How does Nagios support IT infrastructure monitoring?

Nagios provides open-source IT infrastructure monitoring solutions that allow users to monitor websites, servers, switches, routers, firewalls, ports, applications, and metrics. It helps IT professionals prevent downtime and ensure the smooth operation of critical business processes by offering comprehensive visibility into their IT environment.

Which teams benefit most from using Nagios?

Nagios is best suited for IT professionals and organizations that require robust, customizable monitoring of their IT infrastructure. It helps teams manage DevOps and cloud & infrastructure operations by providing detailed insights into system performance and availability.

How is Nagios priced?

Nagios offers a free tier through Nagios Core, which is a community-supported monitoring engine. For users needing more advanced features and support, paid plans are available with Nagios XI, which includes pre-installed plugins, monitoring wizards, and powerful dashboards.

What kind of limitations should users consider when implementing Nagios?

Users should be aware that Nagios has a dated user interface and its configuration can be complex. Additionally, scaling Nagios can be difficult, and the initial setup process may be time-consuming compared to more modern alternatives.

How does Nagios compare to Zabbix for IT monitoring?

Nagios is a legacy monitoring standard known for its high customizability and extensive plugin library, offering a battle-tested open-source solution. While both provide comprehensive monitoring, Nagios is often noted for its more complex configuration and dated UI compared to alternatives like Zabbix.

Can Nagios be extended with additional functionalities?

Yes, Nagios is highly extensible due to its vast plugin architecture and a large community. Thousands of plugins and add-ons are available through Nagios Exchange, allowing users to tailor the monitoring solution to their specific needs.

Does Nagios offer pre-configured solutions for easier deployment?

Yes, Nagios offers the Nagios Core Services Platform (CSP), which is a comprehensive package including essential open-source projects. This platform also provides a pre-configured Nagios XI virtual machine for a unified and streamlined monitoring experience.

Source: nagios.org

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