Server monitoring tools with a free plan in 2026
Host and service monitoring, from the long-running self-hosted systems to hosted agents that report CPU, disk and process health. This list has 26 server monitoring tools. Of these, 20 are open source, 26 have a free plan and 22 can be self-hosted. Checked by hand on 30 September 2026.
- 1
Apache HertzBeat
Agentless monitoring system from the Apache Software Foundation that polls servers, databases, middleware, network devices and websites through templates, with built-in alerting.
- 2
Beszel
Lightweight self-hosted server monitor: a small agent reports CPU, memory, disk, network and Docker container stats to a hub that keeps history and sends alerts.
- 3
Bleemeo
Hosted monitoring for servers, containers and Kubernetes built on an open source agent, with uptime checks, dashboards and alert rules.
- 4
Centreon
IT infrastructure and network monitoring platform that runs Nagios-compatible plugins, offered as open source and as commercial on-premises and cloud editions.
- 5
Checkmk
Infrastructure monitoring for servers, networks, cloud and containers with automatic service discovery; the base edition is open source and paid editions add more.
- 6
Glances
Cross-platform system monitor in Python that shows CPU, memory, disk, network, processes and containers in a terminal, a web UI or a REST API.
- 7
Icinga
Monitoring system that grew out of Nagios: checks hosts and services with plugins, scales across distributed zones, and is configured through files or an API.
- 8
ManageEngine OpManager
On-premises network and server monitoring for routers, switches, firewalls, Windows and Linux hosts and virtual machines.
- 9
Monit
Small Unix daemon that watches processes, files, filesystems and hosts and can restart a service or send an alert when a check fails. M/Monit is the paid central console.
- 10
Monitorable
Hosted Linux server monitoring with a one-command install of an open source OpenTelemetry-based agent, default alert rules, and alerts by email, Telegram, Discord, Slack, ntfy, webhook or PagerDuty.
- 11
Munin
Networked resource monitoring: a master polls lightweight node agents and their plugins and graphs server metrics over time.
- 12
Naemon
Fork of the Nagios 4 core with performance improvements, compatible with Nagios configuration files and plugins.
- 13
Nagios Core
Long-running open source host and service checker with a large plugin ecosystem; Nagios XI is the commercial edition built on it.
- 14
Netdata
Per-second metrics for servers, containers and applications from an agent with built-in dashboards and alerts, plus the optional hosted Netdata Cloud.
- 15
NetXMS
Network and infrastructure management system with SNMP discovery, network maps, server agents and event correlation; an Enterprise edition adds support and features.
- 16
Nezha
Self-hosted monitoring panel for small server fleets: agents report host status and resource use, and the panel can run uptime checks and remote tasks.
- 17
openITCOCKPIT
Monitoring suite that manages Naemon checks through a web interface, with Checkmk and Grafana integration; community and enterprise editions.
- 18
OpenNMS
Network management platform for fault and performance monitoring at scale; Horizon is the open source edition and Meridian the supported one.
- 19
Pandora FMS
Monitoring for servers, networks, applications and logs, with an open source community edition and a commercial enterprise edition.
- 20
PRTG Network Monitor
Windows-based network and server monitoring from Paessler built around sensors for SNMP, WMI, flows, ping and HTTP, with maps and dashboards.
- 21
Scrutiny
Web dashboard for hard drive S.M.A.R.T. data that tracks disk health over time and warns before a drive fails.
- 22
Sensu
Monitoring event pipeline for dynamic infrastructure: agents run checks, and filters and handlers route the results to alerting and metrics tools, all managed as code.
- 23
Simple Observability
Hosted server monitoring that collects metrics and logs through one agent, with dashboards and alerts and little setup.
- 24
Site24x7
Zoho's monitoring suite for websites, servers, networks, applications and cloud, with synthetic transactions and RUM; plain uptime checks have a free plan.
- 25
Xymon
Long-standing system and network monitor that shows host and service status on a color-coded web page, with client agents for host data.
- 26
Zabbix
Open source monitoring for networks, servers, VMs, applications and cloud, using agents, SNMP and templates with trigger-based alerting; Zabbix Cloud is the hosted option.
Side by side
| Tool | Pricing | Free plan | Open source | Self-hosted | Host agent | Agentless checks | Windows hosts | Auto-discovery | Process and service checks | Log collection | Containers | Alerting with notifications | Dashboards | Plugins or integrations |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Apache HertzBeat | Free | Yes | Yes | Yes | No | Yes | Yes | - | Yes | Yes | Yes | Yes | Yes | Yes |
| Beszel | Free | Yes | Yes | Yes | Yes | - | Yes | - | Yes | - | Yes | Yes | Yes | - |
| Bleemeo | Free plan | 3 servers, 5 uptime monitors | No | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Centreon | Free plan | Yes | Yes | Yes | Yes | - | - | Yes | - | Yes | Yes | Yes | Yes | Yes |
| Checkmk | Free plan | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Glances | Free | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | - | Yes | - | Yes | Yes |
| Icinga | Free plan | Yes | Yes | Yes | Yes | Yes | Yes | - | Yes | Yes | Yes | Yes | Yes | Yes |
| ManageEngine OpManager | Free plan | Free edition: 3 devices | No | Yes | Yes | Yes | Yes | Yes | Yes | Yes | - | Yes | Yes | Yes |
| Monit | Free plan | Yes | Yes | Yes | Yes | - | - | - | Yes | - | - | Yes | - | - |
| Monitorable | Free plan | 3 servers | No | No | - | - | - | - | - | - | - | - | - | - |
| Munin | Free | Yes | Yes | Yes | Yes | Yes | - | - | - | - | - | Yes | Yes | Yes |
| Naemon | Free | Yes | Yes | Yes | Yes | Yes | Yes | - | Yes | - | - | Yes | Yes | Yes |
| Nagios Core | Free plan | Yes | Yes | Yes | Yes | Yes | Yes | - | Yes | - | - | Yes | - | Yes |
| Netdata | Free plan | 5 nodes, non-commercial use | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| NetXMS | Free plan | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | - | Yes | Yes | Yes |
| Nezha | Free | Yes | Yes | Yes | Yes | - | Yes | - | Yes | - | - | Yes | Yes | - |
| openITCOCKPIT | Free plan | Yes | Yes | Yes | Yes | Yes | Yes | - | Yes | - | Yes | Yes | Yes | Yes |
| OpenNMS | Free plan | Yes | Yes | Yes | - | Yes | Yes | Yes | Yes | Yes | - | Yes | Yes | Yes |
| Pandora FMS | Free plan | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | - | - | Yes | Yes | Yes |
| PRTG Network Monitor | Free plan | Freeware edition: 100 sensors | No | Yes | - | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Scrutiny | Free | Yes | Yes | Yes | No | No | Yes | - | No | No | - | Yes | Yes | - |
| Sensu | Free plan | Yes | Yes | Yes | Yes | - | Yes | - | - | - | Yes | Yes | Yes | Yes |
| Simple Observability | Free plan | 1 server, 50 metrics | No | No | Yes | - | Yes | Yes | - | Yes | Yes | Yes | Yes | Yes |
| Site24x7 | Free plan | Uptime checks for 50 resources, email alerts | No | No | Yes | Yes | Yes | - | Yes | Yes | Yes | Yes | Yes | Yes |
| Xymon | Free | Yes | Yes | Yes | Yes | - | Yes | - | Yes | Yes | - | Yes | Yes | Yes |
| Zabbix | Free plan | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
Yes: confirmed in the tool's documentation. No: documented as not offered. -: not confirmed. Plans and prices change; check each tool's own site before you decide.
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