GlassWire - Visualize network activity in detail, get notified when new apps access the network, look out for...
Fing Desktop - Device discovery and network monitoring
Little Snitch - Little Snitch is a firewall application that monitors and controls outbound internet traffic.
NetBeez Remote Worker Agent - Simplifying tech support of work from home users.
Radio Silence - Radio Silence is a network monitor and firewall for the macOS. The software stops apps from making network connections. The firewall runs in the background and does not require an open window.
Clearbit's Risk API - Identify spam signups & bad actors