Prometheus - An open-source systems monitoring and alerting toolkit.
Fluentd - Fluentd is a cross platform open source data collection solution originally developed at Treasure Data.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Wazuh - Open Source Host and Endpoint Security
Fluent Bit - Data collector and log forwarder.
Fortinet FortiAnalyzer - Fortinet FortiAnalyzer is a powerful product for Security Fabric Analytics and Automation.