SevOne - SevOne provides network managers with monitoring, troubleshooting, and performance reporting capabilities.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
SolarWinds Network Bandwidth Analyzer - Download a 30-day free trial of Network Bandwidth Analyzer Pack, easy-to-use software that delivers real-time monitoring, alerting, and reporting for routers, switches, and other SNMP-enabled devices.
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Flowmon - Clever Network Monitoring and Security Solution based on NetFlow, IPFIX and Network Behavior Analysis
Nagios - Complete monitoring and alerting for servers, switches, applications, and services