DU Meter - DU Meter is a network bandwidth monitor for your computer.
iStat Menus - "An advanced Mac system monitor for your menubar."
Speedtest.net - Test your Internet connection bandwidth to locations around the world with this interactive broadband speed test from Ookla
Stats - Simple macOS system monitor in your menu bar.
FreeMeter - Monitor network bandwidth (C#.NET 2k/XP+). Desktop and Systray graph.
MenuBar Stats - Advanced Mac system monitor right from the menu bar