- [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.
- [Observium](http://www.observium.org/) - Network monitoring and management platform that provides real-time insight into network health and performance.
- [OMD](http://omdistro.org/) - The Open Monitoring Distribution.
- [Performance Co-Pilot](http://pcp.io) - Lightweight, distributed system performance and analysis framework.
- [PHP Server Monitor](https://www.phpservermonitor.org/) - Open source tool to monitor your servers and websites. ([Source Code](https://github.com/phpservermon/phpservermon))