iStat Menus - "An advanced Mac system monitor for your menubar."
TrafficMonitor - TrafficMonitor is a network monitoring suspension window software in Windows.
iStatistica Pro - System monitor. Reinvented. 💻 🖥
NetBalancer - NetBalancer is a Windows application for local network traffic control and monitoring.
Stats - Simple macOS system monitor in your menu bar.
FreeMeter - Monitor network bandwidth (C#.NET 2k/XP+). Desktop and Systray graph.