The right replacement depends on how much hosting and tuning you're willing to keep doing. Open-source monitors keep the do-it-yourself model, commercial network monitors give you a ready-made sensor approach, and a monitoring-as-code pipeline suits teams that keep checks in version control. Decide who'll maintain the monitoring, then shortlist from that group.
Picture the week a new switch arrives and getting it monitored takes longer than racking it. That's a common moment to start looking past Zabbix: it's free to run, but you host it and tune it yourself, and those hours add up quietly. The eight tools below stick to infrastructure monitoring, carry no ranking and are described from each vendor's or project's own site.
Eight infrastructure monitors, A to Z
One line each, in no particular order of merit, so you can rule names in or out quickly.
Centreon
Best for: Teams after what the vendor calls open, scalable observability from edge to cloud.
Checkmk
Best for: Hybrid IT estates where monitoring should find what runs in the cloud and on-premises, which the vendor says covers everything you run.
LibreNMS
Best for: Network teams wanting automatic discovery over CDP, FDP, LLDP, OSPF, BGP, SNMP and ARP, per the project.
ManageEngine OpManager
Best for: Monitoring routers, switches, firewalls, servers and VMs, with the vendor promising network performance monitoring made uncomplicated.
Netdata
Best for: Fast troubleshooting, with the vendor calling it the fastest path to full-stack observability.
OpenNMS
Best for: Distributed networks with many data points, where the vendor stresses dynamic scalability.
PRTG Network Monitor
Best for: Seeing what's up and what isn't across devices, traffic, systems and applications, in the vendor's own words.
Sensu
Best for: Automated diagnosis and self-healing from bare metal to Kubernetes, as the vendor describes it.
The same eight in a quick table
| Tool | Model | Good for |
|---|---|---|
| Centreon | Open observability platform | Infrastructure, cloud and network in one view |
| Checkmk | Full-stack hybrid monitoring | Auto-discovering cloud and on-premises systems |
| LibreNMS | Open-source network monitor | Auto-discovering network devices |
| ManageEngine OpManager | Commercial network monitor | Routers, switches, firewalls, servers and VMs |
| Netdata | Real-time observability | Per-second metrics for fast troubleshooting |
| OpenNMS | Enterprise network monitoring | Large, distributed networks |
| PRTG Network Monitor | Commercial network monitor | Devices, traffic and applications at a glance |
| Sensu | Observability pipeline | Monitoring checks written as code |
Three camps: open source, sensors and checks as code
Zabbix's newest release talks about observability, APM and OpenTelemetry, per its own site, so it's reaching beyond classic server and network checks. Not every alternative follows it there. They sort into three camps, and the camp matters more than any single feature.
Open-source monitors you run yourself. LibreNMS is a PHP and MySQL network monitor. Centreon unifies infrastructure, cloud, network and digital experience monitoring. OpenNMS describes an enterprise-grade network platform you can deploy anywhere. Netdata leads with per-second metrics, logs and traces, and Checkmk offers full-stack monitoring across cloud and on-premises systems. All five keep you close to the model you know.
Commercial monitors with a ready-made sensor model. PRTG Network Monitor and ManageEngine OpManager both cover devices, servers and traffic with less building on your side. You give up some freedom in exchange for setup that's mostly done for you.
Monitoring as code. Sensu is the odd one out: an observability pipeline where checks are defined as code, which fits teams that already manage infrastructure through version control and code review.
A warning if you're reading older comparisons: zenoss.com now lands on a Virtana page, so any write-up that lists Zenoss as a standalone option may be out of step with what's on sale today.
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Maintain an infrastructure monitor that fits one of these camps? You can submit it for review through the tool form.
Advice: decide who keeps the monitoring alive
Here's where I'd start. The deciding question isn't a feature, it's people. If one admin already spends hours a week tuning templates, an open-source swap moves that work to a new tool rather than removing it. A sensor-based commercial monitor trades some flexibility for less upkeep. If your team writes infrastructure as code, a pipeline approach keeps monitoring inside the same review process as everything else.
Be realistic about the hours, too. Write down how long your team spent on monitoring upkeep over a normal month: new hosts, template tweaks, false alarms, upgrades. That number is the thing you're trying to shrink, and it's a fairer yardstick than any feature comparison.
If you're still mapping the wider field, my server monitoring tools list and network monitoring software guide cover the wider field.
Moving checks across without blind spots
Run both systems side by side for a while. Point the new tool at a handful of critical hosts first, then compare what each one alerts on over the same stretch. Differences tell you where your old templates were doing work you'd forgotten about.
Export your current host list and alert rules before you start, so nothing quietly drops off. Rebuild the alerts that woke someone up recently first; the rest can wait until the core is stable.
Give every alert in the new system a named owner as you rebuild it. Alerts nobody owns are the ones that get muted, and a muted alert is worse than none because everyone assumes it's still watching.
Don't forget the people who only ever read the dashboards. Rebuild the two or three views managers check each morning early, or they'll keep asking for the old system. Switch off the old server only when every host on your list shows up in the new one and the person on call trusts what they're seeing.
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Frequently asked questions
Is open-source monitoring good enough for a small IT team?
Often, yes, if someone on the team is happy to host and maintain it. The software isn't the limit; the hours needed to run it are.
What's the difference between monitoring and observability?
Monitoring checks known things, such as whether a server is up or a disk is full. Observability adds metrics, logs and traces so you can investigate problems you didn't predict.
Can I monitor cloud and on-premises servers with one tool?
Several tools here say they cover both. Check how each one discovers cloud resources and whether it needs an agent on every machine.
How long should I run two monitoring systems in parallel?
Long enough to see a full cycle of your normal alerts, including any weekly or monthly jobs. Switch over once the new system catches everything the old one did.
What happened to Zenoss?
The zenoss.com address now lands on a Virtana page. Check Virtana's own site for what's offered before relying on an older comparison.
