Zabbix is enterprise open source monitoring software for networks and applications.

Pandora FMS (Pandora Flexible Monitoring System) is software for monitoring computer networks.

Cacti is a network graphing solution designed to harness the power of RRDTool's data storage and graphing functionality.

NetCrunch is a Windows Server–based network monitoring tool that boasts high performance and impressive scalability even in a single-server deployment.

HappyApps is an online app uptime monitoring platform.

mention is a social media analytics platform.