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<a href="https://shouldiuse.io/vs/paessler/nagios">Paessler PRTG vs Nagios Open Source on Should I Use It</a>

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Paessler PRTG versus Nagios Open Source
Compare	Paessler PRTG	Nagios Open Source
Verdict	Depends	Depends
Best for	Mid-size to large IT teams	Hands-on sysadmin teams
Who it's not for	Small teams with a few servers . massive overkill	Teams without time to edit config files
Privacy	Vendor publishes security advisories and a Trust Center; two recent PRTG vulnerability advisories found, no breaches reported in sources.	Publicly disclosed and patched vulnerabilities exist; no unpatched crisis in evidence . patch promptly.
Support quality	Large knowledge base and helpdesk; evidence mostly self-serve	No Core support evidence found
Public sentiment	Community sentiment among long-time sysadmins is broadly positive on breadth and reliability, with reviews spread across Spiceworks, Gartner, and Trustpilot.^⁴	Admins rate Core 7.7/10 on TrustRadius across 172 reviews, but Reddit chatter questions how much attention the free version still gets.¹¹
Biggest gotcha	Licensing counts 'sensors' . roughly one monitored metric each; bills multiply fast at scale^²	Core is free, but many features live in paid XI; Reddit users complain the open version lags¹⁵

Pick Paessler PRTG when

Mid-size to large IT teams
Mixed IT/OT industrial environments
NOC and MSP monitoring
On-premises-heavy infrastructure

When Paessler PRTG is not a fit

Small teams with a few servers . massive overkill
Cloud-native shops wanting SaaS-first observability
Anyone who just needs uptime pings for a handful of sites
Teams without time to learn and administer a monitoring platform

Pick Nagios Open Source when

Hands-on sysadmin teams
Self-hosters on a $0 budget
Very large infrastructures (100k+ hosts)
Linux-centric shops

When Nagios Open Source is not a fit

Teams without time to edit config files
Anyone wanting modern dashboards out of the box
Buyers needing vendor SLA support
Non-technical ops staff wanting one-click setup

Sources

Paessler official site / PRTG product pagepaessler.com
official
Paessler pricing pagepaessler.com
official
Paessler PRTG . Wikipediaen.wikipedia.org
news
Spiceworks community discussioncommunity.spiceworks.com
review
Gartner reviews . Paesslergartner.com
review
Trustpilot . Paesslertrustpilot.com
review
Vulnerabilities in PRTG prior v26.2.120.1449helpdesk.paessler.com
security
PRTG in the Cloud press releasepaessler.com
news
Skyscanner case studypaessler.com
official
Nagios Core | The #1 Open Source Monitoring Solutionnagios.org
official
Nagios Core Reviews . TrustRadiustrustradius.com
review
Nagios Open Source . SourceForge reviewssourceforge.net
review
Comparative Analysis of Nagios and OpenNMSacademia.edu
review
Using Nagios as a Groundwork for Better Network Monitoringacademia.edu
review
Is Nagios now mostly commercial and a lot less open? . Redditreddit.com
review
Install Nagios on Ubuntu 20.04cloudinfrastructureservices.co.uk
review