Best network monitoring tools
on Oct 23, 2026
Shortlisting a network monitoring tool is hard. On paper, every tool does the same job: it watches your switches, routers, and servers. The differences are in how each one is run and how you pay for it.
Broadly, they fall into three groups: open-source tools whose vendors also sell a commercial edition, fully commercial platforms, and free open-source tools.
To find the best option for you, ask yourself how many devices you're monitoring, what you can spend, and whether they're on-premises, in the cloud, or both.
TL;DR
- The strongest network monitoring tools come in three kinds: open source with a commercial edition (Checkmk, Nagios), fully commercial (Datadog, LogicMonitor, PRTG, SolarWinds, OpManager), and free open source (Zabbix, Prometheus, LibreNMS).
- Choose based on how many devices you monitor, what you can spend, and whether they run on-premises, in the cloud, or both.
- Pricing units depend on the provider (sensor, node, host, device, or service) and don't map one-to-one, so make sure you understand what each tool charges for before comparing prices.
- Checkmk is the best fit for teams monitoring networks and servers together, from a small setup to 100,000+ hosts on one platform.
The shortlist at a glance
The best network monitoring tools split into three groups: open-source tools whose vendors also sell a commercial edition, commercial platforms, and free open-source tools.
- Checkmk and Nagios make up the first group — free and open source to start, with a commercial edition that adds features and vendor support.
- The fully commercial platforms are Datadog, LogicMonitor, Paessler PRTG, SolarWinds, and ManageEngine OpManager, some with a limited free tier.
- The free open-source options are Zabbix, Prometheus, and LibreNMS.
Checkmk is the best fit for teams that monitor networks and servers together, on-premises and in the cloud, and want to grow to 100,000+ hosts without switching tools.
Tool | Type | Deployment | Pricing model | Typical fit |
|---|---|---|---|---|
Open source + commercial | Self-hosted or SaaS | Per service (free Community edition) | Teams running on-premises and cloud infrastructure on one platform | |
Open source + commercial | Self-hosted | Free Core; commercial XI licensed per node, perpetual | Teams wanting a long-established open-source core | |
Commercial | SaaS | Per device for network devices; per host for infrastructure | Cloud-native teams that also need deep APM | |
Commercial | SaaS | Per device or resource | Enterprises wanting agentless SaaS at scale | |
Commercial (free ≤100 sensors) | Self-hosted or SaaS | Per sensor | SNMP-heavy classic networks | |
Commercial | Self-hosted or SaaS | Per node | Network-centric teams that want path tracing (NetPath) and config management from one vendor | |
Commercial (limited free edition) | Self-hosted | Per device | Budget-conscious on-premises monitoring | |
Open source | Self-hosted (or Zabbix Cloud) | Free; commercial support optional | Teams with time to build and maintain it | |
Open source | Self-hosted | Free | Cloud-native metrics paired with Grafana | |
Open source | Self-hosted | Free | SNMP monitoring of routers and switches |
How many devices do you need to monitor?
Commercial tools usually base pricing on the size of your environment. The tricky part is that every vendor measures that size differently. Paessler PRTG bills by sensor, ManageEngine OpManager and LogicMonitor by device, SolarWinds and Nagios XI by node, Datadog by device for network gear, and Checkmk by service.
And the names aren’t the only difference, as the units don't map one-to-one: a single monitored system can be one node, about ten sensors, or around thirty services. Count what each tool charges for before comparing quotes.
Once you know the size of the environment, it’s much easier to decide. The free tools run at any size, but the building and upkeep grow with the environment, so the real question is how much of that work you want to take on. Checkmk covers both ends: the free Community edition is recommended for around 100 hosts, and Pro and Ultimate run well past 100,000. Because it charges per service, a Wi-Fi access point with a handful of services costs far less than a busy database server with dozens, where per-host pricing would bill the same for both.
Open-source tools with a commercial edition
These tools give you a free, open-source edition and a commercial one alongside it, so you can begin without a license and add commercial features and support as you grow.
Checkmk
Checkmk is a network monitoring tool that polls your switches and routers over SNMP, discovers the services on each, and monitors them alongside your servers from one platform.
A self-hosted Community installation upgrades in place to the commercial Pro or Ultimate edition: the hosts, services, and rules you have set up carry over, so you scale without switching products. Checkmk Cloud is a separate SaaS edition.
Pricing is per service, meaning each thing monitored on a host (a switch port, a file system, or CPU usage), with no per-host fee. Checkmk suits teams running network hardware and servers together, on-premises or across AWS, Azure, and GCP, and because it supports Nagios plug-ins, teams moving off Nagios keep the checks they already built.
How IONOS automates network monitoring for 29 global data centers with Checkmk
IONOS relies on Checkmk’s automation features, like REST API integration and auto-discovery, to streamline monitoring across 29 data centers.
Read the full IONOS success storyNagios
Nagios comes in two forms: the free, open-source Nagios Core, backed by a large community plug-in library, and the commercial XI edition. XI adds a modern web interface, a configuration GUI, and vendor support, licensed perpetually per node with maintenance and support renewed each year. It fits teams that want a long-established open-source core and are prepared to assemble the rest around it.
Nagios Core is bare-bones by comparison — you add plug-ins and external tools for dashboards and graphing, and large check volumes need careful tuning to keep the server from struggling.
Commercial and enterprise tools
These are vendor-supported platforms with no open-source edition. You license the product from the start, though PRTG and OpManager include a limited free tier.
Datadog
Datadog is a SaaS platform built for cloud-native teams. Its deep application tracing, large integration catalog, and one-console view across apps and infrastructure are the draw. For straightforward infrastructure and network monitoring, though, it can be oversized and expensive.
LogicMonitor
LogicMonitor is an agentless SaaS platform for enterprises monitoring at scale, with automated discovery and a large integration library. Its per-resource pricing runs to enterprise budgets, and the strongest AI features are reserved for the top tiers.
Read Checkmk vs. LogicMonitor to discover how the two compare in more detail.
Paessler PRTG
Paessler PRTG is quick to set up for SNMP-heavy classic networks, with a free tier for small setups of up to 100 sensors. Two things set its licensing apart. Each license is tied to a single core server, so an environment that needs more than one core server needs more than one license. And past about 1,000 devices (10,000 sensors), Paessler points you to a different product, PRTG Enterprise Monitor.
See how PRTG compares to Checkmk or take a look at some other PRTG alternatives.
SolarWinds
SolarWinds is a long-established network brand, and its signature NetPath traces hop-by-hop paths across on-premises and cloud. It licenses per node and runs self-hosted or as SaaS.
Network configuration management is included from the Advanced tier of SolarWinds Observability Self-Hosted and still sold as a standalone module, so covering configuration changes alongside performance monitoring means a higher tier or another license.
ManageEngine OpManager
ManageEngine OpManager is an affordable, on-premises option for monitoring infrastructure and virtual machines, licensed per device across Standard, Professional, and Enterprise editions. Its free edition stops at three devices, so it suits a trial, and the Standard edition leaves out agent-based monitoring and REST API access, so automation and server depth need Professional or higher.
Free and open-source tools
These carry no license fee at all. What they cost is build effort: the checks, thresholds, and notifications come together from pieces you set up yourself, and that work grows with the environment. Zabbix sells support subscriptions; Prometheus and LibreNMS rely on their communities.
Zabbix
Zabbix is free, open-source monitoring with SNMP and agent-based collection, and it's flexible enough to adapt to almost any setup. It sits in this group because the whole product is free: there is no commercial edition with extra features, only paid support and a hosted Zabbix Cloud.
What it asks of you is the templates, items, and triggers for anything its library doesn't cover, plus a server-and-database stack to run and tune.
Prometheus
Prometheus pairs metric collection with Grafana dashboards, a combination cloud-native teams know well. It's free to start, and what you pay with is the assembly: an exporter per data source, the queries and dashboards, and the configuration that ties them together. For network devices, that means running the SNMP exporter for your switches and routers and Alertmanager for notifications, each configured and operated separately.
LibreNMS
LibreNMS auto-discovers and polls routers and switches over SNMP, with a clean web interface, network maps, and an active community behind it. It's built around network devices, though: servers mainly come through SNMP, which delivers only basic data compared with an agent, and application monitoring means setting up an extend script for each application on each host.
What happens after a tool finds a device?
Automatic discovery is standard now, and most tools set up basic monitoring once they find a device, but they do differ in how deep that monitoring goes without extra work. This includes how many device types and services the built-in checks cover, and whether the configuration is set per device or by rule.
For example, once a device is in Checkmk, the platform does more than log an inventory entry. It also:
- Recognizes the device by type and manufacturer, and discovers the services worth monitoring on it.
- Applies the right checks automatically, with sensible thresholds from the 2,000+ built-in integrations, so the first alerts already mean something.
- Covers every interface, including ports that are offline at scan time, with a small change to the discovery rule, and tracks port usage over time.
- Scales by rule, so you set a monitoring pattern once instead of configuring every host.
That depth is the point of Checkmk's network monitoring: little of it has to be built by hand, and the network and your servers are on one screen.
Choosing the tool that fits your environment
Work back from your own environment. Count your devices, settle what you can spend, decide whether you'd rather run the tool yourself or have the vendor host it, and the ten names quickly narrow to two or three.
For teams that want networks and servers in one place with room to grow to a large deployment, Checkmk is the one to start with.
- If you'd rather run it yourself, the free, open-source Community edition lets you try it on your own network at no cost.
- If you'd rather not run it at all, Checkmk Cloud is the same platform hosted as SaaS.
See it running first: Play with Checkmk in the interactive demo.
