Best Infrastructure Monitoring Tools

Most infrastructure monitoring tools can draw a CPU chart. That is not what you are choosing between. You are choosing how the data gets collected, what the vendor charges per, and whether the tool still makes sense when the estate is 10 times bigger than it is today. Get one of those three wrong and you will be migrating in 18 months.

This post compares four tools that take different positions on those questions. Pricing was read from each vendor's own site on 2026-10-17, and the cheaper options are not the same tools as the deeper ones, so the "best" one depends on who is running it.

Three Decisions Before You Look at Features#

Agent on every host, or pull from APIs? An agent gives you process lists, disk I/O per device, and metrics every 10 seconds. It also means an installer to roll out, a version to keep current, and a security review for one more binary with root access. Agentless collection reads cloud provider APIs and SNMP instead. Less to install, less detail, and on cloud providers a metrics API bill of its own. Most estates end up with both, which is why a tool that only does one is a problem.

Where does the data live? SaaS tools store your metrics on their side. For most teams that is the whole point. For a team under a data residency rule, or one with an air-gapped network, the question is whether the vendor has a self-hosted edition at all, and what it costs.

What is the billing unit? Per host, per node, per service, or per "whatever the agent reports". This is the one that catches people. Two tools can look equally priced at 20 hosts and differ by 5 times at 500, because one of them counts every container as a host and the other counts them as free.

Four Tools Worth Evaluating#

Datadog Infrastructure#

Datadog is the default answer when a team wants hosts, containers, serverless functions, and the 1,000+ integrations the pricing page advertises all in one SaaS console, with APM and logs one tab away if the budget allows. The Pro tier gives 15 months of metric retention and the stock dashboards; Enterprise adds machine learning alerts, live process views, and a governance console.

The price is per host per month. Pro starts at $15 billed annually or $18 on-demand, and Enterprise at $23 billed annually or $27 on-demand (datadoghq.com/pricing, read 2026-10-17). The free tier is real but small: 5 hosts and 1 day of metric retention, enough to try the agent and not much more.

Where it falls short: the host count is the start of the bill, not the end of it. Containers, custom metrics, and the products that get switched on next to Infrastructure are all priced separately, and the on-demand rate is 20 percent over the annual one. There is no self-hosted edition, so a residency requirement rules it out.

Checkmk#

Checkmk is the opinionated one. Its pricing page argues openly against per-host billing and charges on monitored services instead, with 1 host counted as roughly 30 services. The Community edition is open source and free, and the vendor describes it as comfortable up to about 100 hosts. Pro starts at 190 EUR per month billed annually, which the page works out to about 1.90 EUR per host at the 100-host size. Ultimate adds application observability, cloud integrations, and multi-tenancy from 275 EUR per month. The SaaS version, Checkmk Cloud, is 240 EUR per month on monthly billing, about 7.20 EUR per host (checkmk.com/pricing, EUR view, read 2026-10-17).

The product itself is a classic data center monitor: host and service checks, auto-discovery, SNMP for network gear, hardware inventory, and PDF availability reports. The paid editions claim up to 80 percent less resource use than Community and support for 100,000+ hosts.

Where it falls short: the service based unit cuts the other way when hosts are dense. A box running 80 checks costs more than the headline per-host figure suggests, and the service calculator on the pricing page exists because people get this wrong. The interface is built for operators who already know what a check is; a developer looking for traces will not find them in Pro.

Netdata#

Netdata flips the data residency question. The agent on each node stores and processes the metrics locally, at 1 second resolution, and Netdata Cloud only provides the dashboards and alert routing on top. The free Community tier covers 5 active nodes and 1 custom dashboard, for personal, non-commercial use. Business is $4.50 per node per month billed annually, which the page spells out as $54 per year for 1 node, and includes unlimited retention, role based access, SSO, and an AI troubleshooting feature. Enterprise On-Premise, where the cloud component also runs on your side, starts at 200 node licenses and is quoted by contact (netdata.cloud/pricing, read 2026-10-17).

The billing details are unusually friendly. Containers on a monitored host are not billed, offline nodes are not billed, and the monthly charge is based on the p90 of concurrent agents rather than the peak.

Where it falls short: because the metrics live on the agent, the agent is your database. A node that is wiped takes its history with it unless you have set up a parent node to stream to, which is a piece of architecture the SaaS tools never ask you to think about. And the Community tier's non-commercial clause means a 4-node startup is a Business customer, not a free one.

Zabbix#

Zabbix is the free and open source option in the full sense: the homepage describes deploying it on your own infrastructure as completely free, and the company makes its money on 24/7 support contracts, training, and consulting (zabbix.com, read 2026-10-17). Collection is agent-based, agentless, SNMP, and IPMI, so it covers switches and out-of-band hardware controllers that most cloud native tools ignore.

There is no per-host or per-node license, which at 1,000 hosts is the entire argument. Teams that have run it for a decade tend to keep running it.

Where it falls short: everything the SaaS vendors do for you is yours to do. Database sizing, housekeeping of old data, proxy placement for remote sites, and the upgrade between major versions are all on the operator. The web interface has improved but still reads as a 2010s tool, and the templating model takes real time to learn before the auto-discovery pays off.

The Billing Unit Is the Comparison#

Put the four prices on one 100-host estate, using the annual rates read above, and the ranking is clear before any feature is weighed. Datadog Pro at $15 per host is $1,500 per month. Netdata Business at $4.50 per node is $450. Checkmk Pro at 190 EUR per month is about 1.90 EUR per host. Zabbix is 0, plus whoever runs it.

Then change the shape of the estate rather than the size. Add 10 containers per host and Datadog's bill moves, Netdata's does not, Checkmk's moves if those containers each add services, Zabbix's does not. Replace 50 hosts with network switches and Zabbix and Checkmk are the only two that collect from them without a workaround. Which is why the cheapest line on paper is not always the cheapest one in a year.

Choosing by Situation#

Cloud native team, mostly containers and managed services, budget exists. Datadog. The integrations are already written and nobody has to run anything. Price it with the container and custom metric lines included, not just the host count.

Data center or mixed estate with network gear, and an operator who wants a vendor to call. Checkmk Pro. Run the service calculator first and sanity check the result against your densest hosts.

Small team that wants per second detail, cannot ship metrics to a third party, and has 5 to 200 nodes. Netdata Business. Set up a parent node on day one so a rebuilt host does not lose its history.

Large estate, no license budget, a person who already knows the tool. Zabbix. Treat the Zabbix server and its database as production systems with their own server monitoring.

Whichever you pick, read what infrastructure monitoring covers before buying so the tool matches the scope you actually need, and not the one in the demo.

What None of Them Tell You#

All four tools look at the estate from the inside. That is the right view for a disk filling up at 2 a.m. It is the wrong view for the morning a DNS change sends every user to a dead load balancer while every host underneath reports healthy.

The dashboards will be green. CPU is low because no requests are arriving. The only thing that catches it is a scheduled request from outside your network, hitting the real endpoint and asserting on the status code and the response time. IT monitoring covers why each layer can pass while the one above it fails.

Conclusion#

Infrastructure monitoring tools separate on three things: how they collect, where the data lives, and what they bill per. Datadog is the broadest SaaS at the highest per-host price, Checkmk is the data center tool with service based pricing and a free edition for small estates, Netdata is the cheap per-node option that keeps metrics on your hosts, and Zabbix is free to license and expensive in operator time.

ObserveOne covers the outside-in half: uptime and API checks from multiple regions, so a healthy fleet and an unreachable application never read as the same green dashboard.