Little Snitch - Little Snitch is a firewall application that monitors and controls outbound internet traffic.
ZoneAlarm Free Firewall - Personal Firewall software
LuLu by Objective-See - LuLu is the free open-source macOS firewall that aims to block unauthorized (outgoing) network...
Comodo Firewall - Comodo Firewall Pro - Secure your system against internal attacks such as Trojan viruses /...
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.
TripMode - Manage your Mac's broadband usage while on a hotspot