Little Snitch

Little Snitch is a host-based application firewall for macOS. It can be used to monitor applications, preventing or permitting them to connect to attached networks through advanced rules. It is produced and maintained by the Austrian firm Objective Development Software GmbH.

Unlike a stateful firewall, which is designed primarily to protect a system from external attacks by restricting inbound traffic, Little Snitch is designed to protect privacy by limiting outbound traffic. Until Little Snitch 4, it controlled network traffic by registering kernel extensions through the standard application programming interface (API) provided by Apple, but at version 5 it switched to using Apple's Network Extensions due to the deprecation of kernel extensions on macOS Catalina.

When an application or process attempts to establish a network connection, Little Snitch presents a dialog that allows the user to deny or permit the connection once, for a limited time, or permanently. The dialog also allows the user to restrict the parameters of the connection, for example allowing a given application to only connect to a certain domain or using a specific protocol or port. Little Snitch's integral network monitor shows ongoing traffic in real time with domain names and traffic direction.

The application (version 4) received a positive 4.5/5 review from Macworld.