Top Alternatives to Pandora FMS

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

Nagios known as Nagios Core, is a free and open source computer-software application that monitors systems, networks and infrastructure.

Datadog is a monitoring service for cloud-scale applications, bringing together data from servers, databases, tools, and services to present a unified view of an entire stack.

PRTG is a network monitoring tool that helps you to ensure that your computer systems are running smoothly and that no outages occur.

Icinga is an open source computer system and network monitoring application.

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

The Dude network monitor automatically scans all devices within specified subnets, draw and layout a map of your networks, monitor services of your devices and alert you in case some service has problems.