macOS features one of the best network firewalls: PF (Packet Filter). It comes in an "under the hood" fashion, installed and disabled by default.
Murus' purpose is to unleash its potential. With its easy and intuitive icons-based and drag&drop-based interface, visual layers of abstraction and a friendly views of the PF firewall, it's a lean and mean tool to protect your Mac and network.
Vallum is a little tool that helps you increase your privacy and security. It is able to intercept apps connections and hold them while you decide whether to pass or block them. It can be used to increase your privacy or to transparently protect non-admin users from unwanted connections on multi-user macs. Vallum simple interface can be used by everybody to configure the outbound application-layer firewall, its default configuration is not intrusive and it does not require any interaction or specific knowledge or maintenance.Visit Vallum Web Site