OpenSnitch - https://github.com/evilsocket/opensnitch
2023 - Opensnitch, application level interactive firewall, heading into Debian
Douane - https://douaneapp.com/
Gufw - http://gufw.org/
Leopard Flower - https://github.com/themighty1/lpfw
Macintosh only
Little Snitch - https://www.obdev.at/products/littlesnitch
LuLu - https://objective-see.org/products/lulu.html (github)
2023 - Opensnitch, application level interactive firewall, heading into Debian
Douane - https://douaneapp.com/
Gufw - http://gufw.org/
Leopard Flower - https://github.com/themighty1/lpfw
Macintosh only
Little Snitch - https://www.obdev.at/products/littlesnitch
LuLu - https://objective-see.org/products/lulu.html (github)