Nagios - Complete monitoring and alerting for servers, switches, applications, and services
Wazuh - Open Source Host and Endpoint Security
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Beats - Beats is the platform for single-purpose data shippers that is installed as lightweight agents and send data to machines to Logstash or Elasticsearch.
Checkmk - Checkmk - the software for effective IT monitoring
Syslog-ng - Syslog-ng decreases the quantity and improves the quality of data, thus enhancing the capacities of your SIEM solution.