glogg

glogg is a multi-platform GUI application to browse and search through long or complex log files.
BareTail

BareTail is a real-time log file monitoring tool.
Features
Real-time file viewing.
OP5 Monitor

OP5 Monitor – The enterprise level open source monitoring solution that allows users to have complete control over their IT infrastructure.
VividCortex

The best way to monitor your production databases.
Server Density

Trusted monitoring built by experts.
OpsDash

All-in-one solution for monitoring servers, services, uptime and databases. Curated Dashboards. Rule-based alerting.
TraceView

Ridiculously Detailed Application Monitoring.
openITCOCKPIT

openITCOCKPIT is a leading open source monitoring framework based on Naemon (Nagios). In addition it integrates Checkmk and Prometheus. It also offers interfaces to Icinga2, PRTG and opManager to obtain status and performance from them.
The Dude

MikroTik is a Latvian company which was founded in 1996 to develop routers and wireless ISP systems. MikroTik now provides hardware and software for Internet connectivity in most of the countries around the world.
nxlog

NXLog offers log management solutions for companies of all sizes.