Self-hosted, lightweight server and website monitoring and O&M tool
The Network UPS Tools repository
A suite of Monitoring Plugins (formerly known as nagios-plugins)
A utility to safely generate malicious network traffic patterns
The Active Monitoring System
Lightweight network IP scanner
BGP and RPKI monitoring tool
Office Tool Plus localization projects
pg_activity is a top like application for PostgreSQL server activity
Monitor temperature sensors, fan speed, voltage, load & clock speeds
Floating window used to display current network speed, CPU & memory
Open-source systems performance monitor
An eye on your system
Monitorix is a free, open source, lightweight system monitoring tool
A fancy self-hosted monitoring tool
The open source time series database
High performance ping tool
A Swiss army knife for your daily Linux network plumbing
Network Enumeration Tool for Host Exploration and Recon
Discourse Network Analyzer (DNA)
Collect and display information and stats from a running PostgreSQL
Zeek is a powerful network analysis framework
A system monitoring tool that exposes system metrics
Application to comfortably monitor your Internet traffic
Free open source tool for real-time PC hardware sensor monitoring