productboard - Beautiful and powerful product management.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
FastNetMon - FastNetMon is a very fast DDoS analyzer with sflow/netflow/mirror support.
Observium - Observium
ProdPad - ProdPad helps your team gather ideas, surface the best ones and turn them into product specs, and then put it all on a product roadmap.
Nagios - Complete monitoring and alerting for servers, switches, applications, and services