SecurityOnion - Security Onion is a free and open source Linux distribution for intrusion detection, enterprise security monitoring, and log management.
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.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
AppDynamics - Get real-time insight from your apps using Application Performance Management—how they’re being used, how they’re performing, where they need help.
Suricata - Suricata is a high performance Network IDS, IPS and Network Security Monitoring engine.
Wazuh - Open Source Host and Endpoint Security