System monitors

task manager program found in many Unix-like operating systems. It produces an ordered list of running processes selected by user-specified criteria, and updates it periodically

Nagios () is an open-source network and infrastructure monitoring system. It monitors hosts, services, and network devices, sending alerts when components fail and again when they recover. Originally written by Ethan Galstad in 1999 as NetSaint, it was renamed Nagios in 2002 after a trademark dispute. The name is a recursive acronym: "Nagios Ain't Gonna Insist On Sainthood."

Zabbix is an open-source monitoring platform for networks, servers, virtual machines, and cloud services. It collects metrics via SNMP, IPMI, JMX, and custom agents, then stores the data in a relational database and provides alerting, visualization, and reporting through a web-based frontend.

Grafana is an open-source analytics and visualization web application. It connects to time series databases and other data sources, allowing users to build dashboards that display metrics, logs, and traces. Grafana supports data sources including Prometheus, Graphite, InfluxDB, Elasticsearch, PostgreSQL, and MySQL.

htop is an interactive system monitor process viewer and process manager. It is designed as an alternative to the Unix program top.

System monitor for X

Datadog, Inc. is an American company that provides an observability service for cloud-scale applications, providing monitoring of servers, databases, tools, and services, through a SaaS-based data analytics platform. Founded and headquartered in New York City, the company is a publicly traded entity on the Nasdaq stock exchange.

GNU Krell Monitors (GKrellM) is a computer system monitor package based on the GTK+ toolkit that creates a single process stack of system monitors. It can be used to monitor the status of CPUs, main memory, hard disks, network interfaces, local and remote mailboxes, and many other things. Plugins are available for a multitude of tasks, e.g., controlling the XMMS media player or a SETI@home client from within the stacked monitor.

hardware or software component used to monitor system resources and performance in a computer system

Icinga is an open-source network monitoring system created in 2009 as a fork of Nagios. The project was started by a group of Nagios community developers who cited slow development, limited community input, and insufficient handling of contributed patches as reasons for the fork. The name is a Zulu word meaning "it looks for" or "it examines."

software for monitoring computer networks

event monitoring and alerting software

free tool from Windows Sysinternals, part of the Microsoft TechNet website.

software tool

monitoring application

Checkmk is an open source IT infrastructure monitoring software system developed in Python and C++. It originated as an extension to Nagios and has since evolved into a self-contained monitoring platform.