"Network monitoring tools" turns up a genuinely mixed bag of results: free software you install yourself, device-based commercial platforms, and per-host add-ons bolted onto a broader observability suite. Those aren't competing versions of the same thing, they're three different ways to pay for the same job, and which one makes sense depends more on your team's time budget than on a feature checklist.
This post groups the real options into those three buckets, with the actual numbers behind each one.
The Three Ways to Pay for This#
Open-source, self-hosted. No license fee. You run the software, maintain the server, write the polling configs, and own the upgrades. The cost shows up as engineering time, not a monthly invoice.
Dedicated network monitoring platforms. Commercial software built specifically for SNMP polling, device discovery, and network topology. Priced by device or sensor count, with support included.
Add-on inside a broader observability platform. If you're already paying for infrastructure or APM monitoring, network visibility is sometimes a module you turn on rather than a separate purchase, priced per host like the rest of the platform.
Open-Source Stacks#
Zabbix, Nagios, and LibreNMS are the three that show up most often in this category. All three poll devices over SNMP or agent, store time-series data, and alert on thresholds, with no license cost attached to any of them. Zabbix bundles a web UI and templates for most common network gear out of the box; LibreNMS leans on auto-discovery and is popular specifically for network-device inventories; Nagios is the oldest of the three and has the largest plugin ecosystem, at the cost of a dated interface.
None of these have a price to fetch, because the software itself is free. The real cost is the server it runs on, and the time to configure device templates, tune alert thresholds, and keep the install patched. For a small network with someone who already knows SNMP, that's a reasonable trade. For a team that wants to install something and have it working the same afternoon, it usually isn't, since there's no vendor support line to call when a polling job silently stops.
Dedicated Network Monitoring Platforms#
| Tool | Licensing unit | Starting price (read 2026-10-22) |
|---|---|---|
| Paessler PRTG Network Monitor | Devices / sensors | $200/month paid annually for PRTG 500 (50 devices), scaling to $1,642/month for PRTG 10000 (1,000 devices) |
| SolarWinds Network Performance Monitor | Elements (nodes, interfaces, volumes) | No public list price. Quote-only through SolarWinds sales as of this run |
Paessler PRTG Network Monitor#
PRTG prices by how many devices you're watching, not by feature tier, so every plan includes the same monitoring capability (paessler.com/pricing, read 2026-10-22). PRTG 500 covers 50 devices at $200/month billed annually; PRTG 1000 covers 100 devices at $358/month; the range runs up to PRTG 10000 at $1,642/month for 1,000 devices. Paessler also sells PRTG Enterprise Monitor above that tier, quote-only.
Where it falls short: the per-device pricing means a network with a lot of small devices (every access point, every UPS, every printer) climbs the pricing ladder fast, even if each one only needs a handful of basic checks. A 300-device network lands in PRTG 2500 territory at $742/month, regardless of how simple those 300 devices are to monitor.
SolarWinds Network Performance Monitor#
SolarWinds NPM is the other name that comes up constantly in this category, and as of this run its public pricing page returns a 404; the current product page (solarwinds.com/network-performance-monitor, read 2026-10-22) routes every pricing question to "Contact Sales for a custom quote." That's a change from SolarWinds' historical per-element public pricing, and it means a cost comparison against PRTG currently requires a sales call rather than a published number.
Where it falls short right now, specifically: you can't budget against it without engaging sales first, which rules it out for a team that wants to compare total cost of ownership before anyone picks up the phone.
As an Add-On to a Broader Platform#
If your infrastructure monitoring is already on a per-host observability platform, network visibility is sometimes a line item inside that same pricing rather than a separate product. Datadog is the clearest example: its core Infrastructure Monitoring starts at $15/host/month billed annually (datadoghq.com/pricing, read 2026-10-22), and Network Monitoring ships as an add-on inside the same per-host billing model rather than as a separately listed public per-host rate.
This path makes sense specifically when you're already paying Datadog, or a platform priced the same way, for application and infrastructure monitoring, and want network device and traffic data in the same dashboards without standing up a second tool. It makes less sense as a first network monitoring purchase: you'd be buying infrastructure-wide observability to get network visibility, when a $200/month PRTG license or a self-hosted Zabbix instance does the core SNMP-polling job without the rest of the platform attached.
Choosing by Situation#
Small network, in-house SNMP expertise, no budget for licensing. Zabbix or LibreNMS. The setup cost is real but one-time; there's no recurring per-device meter running.
Mid-size network, want vendor support and a working install fast. PRTG. The per-device pricing is predictable and the product is purpose-built for exactly this job.
Large enterprise network, procurement already runs through a vendor relationship. SolarWinds NPM, but budget time for the sales conversation before you can put a number on it.
Already running Datadog (or similar) for infrastructure and application monitoring. Add Network Monitoring as a module rather than standing up a fourth tool.
What None of Them Catch#
Every tool on this list watches the network from the inside: SNMP polling, flow collection, device health, all measured from a vantage point inside your own infrastructure. That's the right lens for "is this router healthy" and the wrong one for "can a user outside our network actually reach the service." A fully healthy, fully polled network can still sit behind a DNS misconfiguration or an expired certificate that none of these tools would flag, because nothing inside the network is unhealthy. ObserveOne runs scheduled checks from outside your infrastructure specifically to catch that gap, the one none of the tools above are built to see.
Conclusion#
Open-source stacks trade a license fee for setup and maintenance time. PRTG prices predictably by device count and scales cleanly as your network grows. SolarWinds NPM is quote-only as of this run, which puts it last for anyone trying to budget without a sales call. Datadog's Network Monitoring is worth it only once you're already paying for the rest of the platform it rides on.
Pick based on who's maintaining it and what you're already paying for elsewhere, not on brand recognition. ObserveOne covers the outside-in check none of these tools do on their own.