All 11 reviews, filed by the job they do best

Self-hosted monitoring for servers, network devices and applications, built around templates, discovery rules and a SQL history store.

OK

Template library covers most common servers and switches on day one

WARN

History and trend tables grow fast — plan partitioning or TimescaleDB early

CRIT

Not a quick win: expect days of template tuning before alerts are trustworthy

The long-running host and service checking engine whose plugin interface much of the monitoring world still speaks.

OK

Tiny footprint and predictable behavior once configured

WARN

Every host and service lives in hand-edited object files

CRIT

No built-in graphing or modern UI — you bolt those on yourself

Community-run network monitoring that discovers SNMP devices, graphs every port and alerts on what changed.

OK

Point it at a subnet with SNMP credentials and ports are graphed within the hour

WARN

Default five-minute polling hides short spikes; faster polling costs CPU

CRIT

Server and application checks are thin compared with Zabbix or Checkmk

Paessler’s commercial monitoring platform, licensed by sensor count and available self-managed or as a hosted service.

OK

Discovery creates sensible sensors quickly; vendor support is included

WARN

Licensing is by sensor count, and sensors add up faster than you expect

CRIT

The self-managed core server runs on Windows only

Commercial network and server monitoring from ManageEngine, licensed per device with modules for flow analysis and configuration management.

OK

Runs on Linux as well as Windows, which PRTG and SolarWinds do not

WARN

Flow analysis and config backup are separate add-ons with their own pricing

CRIT

The interface is dense; finding the right setting takes practice

SolarWinds’ enterprise network performance monitor, now sold within its self-hosted observability platform.

OK

Deep network visibility and mature reporting for large estates

WARN

Needs Windows Server plus SQL Server capacity of its own

CRIT

Cost and platform weight are hard to justify for small teams

A Nagios-plugin-compatible monitoring stack with its own configuration language, clustering and a modern web front end.

OK

Apply rules and the Director module make large configs manageable

WARN

Several moving parts: Icinga 2, Icinga DB, Redis, Icinga Web

CRIT

Metrics graphs need a separate backend such as Graphite or InfluxDB

Agent-based monitoring that discovers services automatically and ships with a large set of checks, in an open Raw edition and paid editions.

OK

Fastest route here from empty server to a useful dashboard

WARN

Some features you will want (agent bakery, faster core) are in paid editions

CRIT

Rule precedence can surprise you when several rules match one host

A small, open-source desktop scanner that sweeps IP ranges, reports which hosts answer, resolves names and probes chosen TCP ports.

OK

Sweeps a /24 in moments and exports a list you can diff against your monitoring inventory

WARN

A point-in-time snapshot: nothing is stored, scheduled or alerted on

CRIT

TCP ports only — it cannot tell you whether SNMP on UDP 161 will answer your poller

The widely used open-source packet analyzer: capture traffic or open a saved capture, then decode it protocol by protocol.

OK

Settles “is the packet even arriving?” arguments in minutes

WARN

Captures need privileges, disk space and a careful filter to stay useful

CRIT

A diagnostic instrument, not a monitor: no polling, history or alerting

A closed-source Windows scanner that sweeps IP ranges for shared folders, FTP and web servers, and shows which of them a given account can read or write.

OK

Answers “which shares can this service account actually write to?” across a whole range

WARN

Latest release is v21.07 from July 2021; Windows 11 is not on the vendor’s supported list

CRIT

Windows-only and closed source, with no port scan, SNMP or IPv6 claims — a narrow tool