Hands Off! Alternatives for Mac OS X

Little Snitch is an essential network monitoring and firewall tool for macOS. It provides granular control over your Mac's network connections, alerting you whenever an application attempts to connect to the internet and allowing you to decide whether to permit or deny the connection.

Radio Silence is a macOS firewall designed to easily monitor and block unwanted network connections from applications, enhancing your privacy and security by preventing apps from sending data out without your consent.