- [eZ Server Monitor](http://www.ezservermonitor.com) - A lightweight and simple dashboard monitor for Linux, available in Web and Bash application. ([Source Code](https://github.com/shevabam/ezservermonitor-web)) `GPL-3.0``PHP/Shell`
- [Healthchecks](https://healthchecks.io/docs/self_hosted/) - Monitoring for cron jobs, background services and scheduled tasks. ([Source Code](https://github.com/healthchecks/healthchecks)) `BSD-3-Clause``Python`
- [Icinga](https://www.icinga.com/) - Nagios fork that has since lapped nagios several times. Comes with the possibility of clustered monitoring. ([Source Code](https://github.com/Icinga/icinga2)) `GPL-2.0``C++`
- [LibreNMS](http://www.librenms.org) - Fully featured network monitoring system that provides a wealth of features and device support. ([Source Code](https://github.com/librenms/librenms))
- [LibreNMS](http://www.librenms.org) - Fully featured network monitoring system that provides a wealth of features and device support. ([Source Code](https://github.com/librenms/librenms))`GPL-3.0``PHP`
- [Linux Dash](https://github.com/afaqurk/linux-dash) - A low-overhead monitoring web dashboard for a GNU/Linux machine. `MIT``Nodejs/Go/Python/PHP`
- [Monit](http://mmonit.com/monit/#home) - Small utility for managing and monitoring Unix systems. ([Source Code](https://bitbucket.org/tildeslash/monit/src/master/))
- [Naemon](http://www.naemon.org/) - Network monitoring tool based on the Nagios 4 core with performance enhancements and new features. ([Source Code](https://github.com/naemon/naemon-core))
- [Netdata](https://www.netdata.cloud/) - Distributed, real-time, performance and health monitoring for systems and applications. Runs on Linux, FreeBSD, and MacOS. ([Source Code](https://github.com/netdata/netdata))
- [NetXMS](https://www.netxms.org/) - Open Source network and infrastructure monitoring and management. ([Source Code](https://github.com/netxms/netxms))
- [Monit](http://mmonit.com/monit/#home) - Small utility for managing and monitoring Unix systems. ([Source Code](https://bitbucket.org/tildeslash/monit/src/master/))`AGPL-3.0``C`
- [Naemon](http://www.naemon.org/) - Network monitoring tool based on the Nagios 4 core with performance enhancements and new features. ([Source Code](https://github.com/naemon/naemon-core))`GPL-2.0``C`
- [Netdata](https://www.netdata.cloud/) - Distributed, real-time, performance and health monitoring for systems and applications. Runs on Linux, FreeBSD, and MacOS. ([Source Code](https://github.com/netdata/netdata))`GPL-3.0``C`
- [NetXMS](https://www.netxms.org/) - Open Source network and infrastructure monitoring and management. ([Source Code](https://github.com/netxms/netxms))`LGPL-3.0/GPL-3.0``Java/C++/C`
- [Observium](http://www.observium.org/) - SNMP monitoring for servers and networking devices. Runs on linux.
- [OMD](http://omdistro.org/) - The Open Monitoring Distribution.
- [Performance Co-Pilot](http://pcp.io) - Lightweight, distributed system performance and analysis framework.