Best Open-Source System Monitors 2026: 6 Options Compared

System monitors range from a terminal view of one machine to platforms that watch hundreds of servers, so start by deciding which you need. For a single computer, btop++ and htop are terminal programs that show CPU, memory, disks, network and processes in real time. btop is graphical-looking with graphs, while htop is leaner and available almost everywhere. Glances is a Python tool that combines many views and can also serve a web interface, which makes it handy for checking a remote box without SSH. For several machines, Netdata gives per-second dashboards with little configuration, though its cloud service has its own free limits and the UI is not fully open source. Zabbix is an all-in-one monitoring platform with alerts, and Prometheus collects metrics for storage and querying and pairs with a dashboard tool, so it takes more assembly. The trade-off is setup against depth: a terminal monitor installs in seconds but forgets everything when you close it, while a monitoring platform keeps history and sends alerts, at the cost of a server to run and rules to tune. For a home server or a workstation, btop or Glances is usually enough. Add Prometheus or Zabbix once you want to be told when something fails, rather than checking by hand.

btop++

Apache-2.0 terminal monitor with graphs for CPU, memory, disks, network and processes. Easy to install and good to look at.

Price: Free (Free open source) (btop++ pricing, checked 2026-10-24).

Platforms and license: Linux, macOS, FreeBSD. Apache-2.0 (open source) (license source).

Project activity: 35.1k GitHub stars · latest release v1.4.8 (Oct 25, 2026) · last commit Oct 25, 2026

Best for: A single machine at a glance.

Worth knowing: Terminal resource monitor for CPU, memory, disks, network and processes.

htop

GPL-2.0 interactive process viewer for the terminal, available on most systems. Leaner than btop, with fewer graphs.

Price: Free (Free open source) (htop pricing, checked 2026-10-24).

Platforms and license: Linux, macOS, BSD. GPL-2.0 (open source) (license source).

Project activity: 8.4k GitHub stars · latest release 3.5.3 (Aug 16, 2026) · last commit Oct 19, 2026

Best for: Fast process inspection.

Worth knowing: Interactive process viewer for the terminal.

Glances

LGPL-3.0 Python monitoring tool with terminal and web interfaces. Covers many metrics in one view.

Price: Free (Free open source) (Glances pricing, checked 2026-10-24).

Platforms and license: Linux, macOS, Windows. LGPL-3.0 (open source) (license source).

Project activity: 33.9k GitHub stars · latest release v4.5.8 (Oct 11, 2026) · last commit Oct 26, 2026

Best for: Checking a box through a browser.

Worth knowing: Python monitoring tool with terminal and web interfaces.

Netdata

GPL-3.0+ agent with per-second dashboards across nodes; the cloud tier is limited to 5 nodes for personal non-commercial use on its free plan, and the UI is closed source.

Price: Free (Cloud Community: 5 active nodes, personal non-commercial use); paid from $4.5 per node/month (Business) (Netdata pricing, checked 2026-10-22).

Platforms and license: Linux, macOS, Windows, FreeBSD, Docker, Kubernetes. GPL-3.0+ (Agent); UI and Cloud closed source (open source) (license source).

Project activity: 81.2k GitHub stars · latest release v2.12.2 (Oct 23, 2026) · last commit Oct 27, 2026

Best for: Quick multi-server dashboards.

Worth knowing: Homelab plan is $90 per year for unlimited nodes, non-commercial.

Zabbix

AGPL-3.0 platform for monitoring servers, networks and applications with alerting. Complete, but it takes setup and tuning.

Price: Free (Zabbix pricing, checked 2026-10-22).

Platforms and license: Self-hosted, Zabbix Cloud. AGPL-3.0 (7.0 and later); GPL-2.0 up to 6.4 (open source) (license source).

Project activity: 6.5k GitHub stars · last commit Oct 27, 2026

Best for: Alerts and history for many hosts.

Prometheus

Apache-2.0 metrics collection and query system. Usually paired with a separate dashboard tool, so it needs more assembly.

Price: Free (Prometheus pricing, checked 2026-10-22).

Platforms and license: Self-hosted (Go binary). Apache-2.0 (open source) (license source).

Project activity: 66.8k GitHub stars · latest release v3.15.1 (Oct 21, 2026) · last commit Oct 27, 2026

Best for: Metrics for cloud and containers.

Worth knowing: Metrics and alerting only; no built-in dashboards beyond a basic expression browser, so it is usually paired with Grafana.

Which one to pick

• You want a quick look at one Linux machine: btop++
• You want a lightweight process viewer everywhere: htop
• You want a dashboard for several servers fast: Netdata
• You need alerts and history for many hosts: Zabbix