GlassWire - Visualize network activity in detail, get notified when new apps access the network, look out for...
Gufw - Gufw is an easy, intuitive way to manage your Linux firewall.
TinyWall - Lightweight and non-intrusive firewall
Windows 10 Firewall Control - Windows 10 Firewall Control: simple and exhaustive solution for applications network activity controlling and monitoring.
Little Snitch - Little Snitch is a firewall application that monitors and controls outbound internet traffic.
Firestarter - Firestarter is an Open Source visual firewall program.