Zabbix vs PRTG for a small network
The usual comparison stops at "Zabbix is free, PRTG is licensed per sensor". That is true and it is also the least useful thing to know. What decides the outcome is who maintains it and what happens at 2am when it goes quiet.
The short answer
- PRTG if nobody on staff will own the monitoring system, you want it working this week, and the sensor count is small and stable.
- Zabbix if you have someone who can learn it, the estate changes often, and you need history and correlation rather than a green dashboard.
- Neither if you deploy it and never tune it. An untuned system is worse than none, because it trains people to ignore alerts.
What each one actually costs
PRTG's pricing is per sensor. A sensor is roughly one thing you monitor on one device — a port, a disk, a service, a ping. A 48-port switch with interface monitoring is 48 sensors before you have monitored anything else. At that point a 100-sensor free tier and a few thousand dollars of licence is the reality for a mid-size closet.
Zabbix is free under GPL. The cost is not zero, it is labour: installing the server, deciding on a database, sizing history retention, writing templates for anything unusual, and building dashboards someone will read. That labour is the product you are actually buying when you hire someone, and it is why official Zabbix consulting is priced per engagement rather than per host.
Where PRTG is genuinely better
Discovery and first-run experience. Point it at a subnet, give it credentials, and it finds devices and proposes sensors. The UI is a tree, which matches how network people think. For a 40-device network with one person who has ninety other things to do, that is worth real money.
Where Zabbix wins
- Scale without a licence cliff. Adding 200 interfaces costs nothing but polling capacity.
- Real history. Trending and long-term data are first-class, not an add-on.
- Correlation and triggers. Dependencies, hysteresis, and suppression are how you stop alert storms — PRTG can do some of this, Zabbix is built around it.
- Agents and log monitoring in the same system. Host metrics, Windows services, and log-derived triggers without a second tool.
The part nobody puts in the comparison table
Both tools fail the same way: the install works, the defaults are noisy, nobody tunes thresholds, and within a month the alerts are filtered into a folder nobody reads. The difference between a monitoring system and a monitoring outcome is about two weeks of tuning against a real baseline — which specific alerts are actionable, which should be dependencies rather than pages, and what "normal" looks like on a Tuesday.
If you are doing that yourself, budget the two weeks. If you are buying it, that tuning is the thing to insist on in the statement of work, not the installation.
A decision rule that works
Count the people who will touch the monitoring system after it is built.
- Zero — buy the one with the support contract and the simplest UI. PRTG or a managed service.
- One, part-time — Zabbix is viable but only with a proper handover and a runbook.
- One, dedicated — Zabbix, and invest in templates and dependencies early.
If you inherit a Zabbix that nobody trusts
The fix is rarely a reinstall. It is usually: delete or downgrade the alerts nobody acts on, add dependencies so a core switch failure does not generate forty pages, set retention deliberately, and write down what each remaining trigger means. That work is unglamorous and it is most of what a deployment engagement actually is.
I deploy Zabbix and Wazuh for networks of 50–500 devices as a fixed-scope engagement — installed, tuned against your baseline, documented, and handed over with thirty days of tuning. Details and pricing are here. If you would rather do it yourself, the starter kit has the automation scripts that make the repetitive parts bearable.