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Nagios vs Zabbix
Zabbix is free and fully featured with paid support as an option; Nagios keeps its engine free but gates the web UI and reporting behind paid XI.
Side by side
| Nagios | Zabbix | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Vendor | Nagios Enterprises | Zabbix SIA | ||||||||
| Pricing model | Free tier + paid plans | Open source + paid options | ||||||||
| Free tier | Yes | Yes | ||||||||
| Deployment | Self-hosted | Self-hosted, Cloud | ||||||||
| Open source | Yes (GPL-2.0) | Yes (AGPL-3.0) | ||||||||
| Best for | IT teams wanting a proven, self-hosted monitoring engine, free at the core with a paid path to a web UI and reporting. | Teams that want a free, unlimited, self-hosted monitoring platform with an optional paid support contract. | ||||||||
| Pricing | Nagios Core is free and open source; Nagios XI is a perpetual license priced by monitored node count, with an Enterprise add-on tier.
Prices read from the vendor's own page on September 21, 2026. Vendors change prices; check the source before you budget. | The software is free and fully featured with no host/metric limits; paid tiers are optional support subscriptions, not feature gates.
Prices read from the vendor's own page on September 21, 2026. Vendors change prices; check the source before you budget. | ||||||||
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Verdict
Both are long-standing, self-hosted, open-source tools for monitoring the health of devices, servers and services, and both remain common defaults for teams that want to own their monitoring stack rather than pay per-node to a SaaS vendor. The difference is where the free line is drawn. Zabbix is entirely free and open source with no artificial limits on hosts, metrics or users — every feature is unlocked in the free software, and what Zabbix sells is optional vendor-backed support subscriptions with response-time SLAs. Nagios Core, the underlying engine, is also free, but it is configured through text files and plugins with no built-in web UI; what most organizations actually deploy is Nagios XI, a perpetually licensed product built on the same engine that adds web-based configuration, auto-discovery, dashboards and SLA/capacity reporting.
So the practical comparison is Zabbix's free, fully-featured product against Nagios's free-but-manual core plus a paid step up to something usable day-to-day by a team that doesn't want to hand-edit config files.
Choose Zabbix if
- You want a modern web UI, auto-discovery and unlimited hosts without paying anything beyond your own infrastructure and time.
- You might want vendor support later and prefer that to be an optional add-on rather than a required license to unlock basic usability.
- You want built-in anomaly detection and trend prediction without a third-party plugin.
Choose Nagios if
- Your team is comfortable configuring Nagios Core via text files and plugins and doesn't need a web UI, in which case it costs nothing to run.
- You want Nagios XI specifically for its very large, decades-old plugin ecosystem and are willing to pay a perpetual per-node license for the web UI and reporting.
- You're already standardized on Nagios and evaluating whether to move, rather than starting fresh.
The honest caveat
"Free" for either tool means free of license cost, not free of ongoing effort — both require someone to configure checks, maintain the install, and respond to alerts, which is a real and recurring cost regardless of which one you pick. If your team has no appetite for that operational ownership, a SaaS alternative such as Auvik may suit you better than either. See data observability.
Last reviewed September 22, 2026