Little Snitch remains one of my favorite apps in the personal privacy protection category. Created by Objective Development, Little Snitch monitors your outgoing connections to the Internet and pops up to let you know when an application is trying to send data behind your back.
Little Snitch 3
Improvements in Little Snitch 3 include a new network monitor that has been redesigned to provide clear and detailed information about your Mac's network activity. Also new is Silent Mode, which prevents Little Snitch from interrupting your activity to tell you about network connections. Instead, it maintains logs about attempted connections that you can review at a more convenient time.
Little Snitch has always been a great outbound network firewall; it now includes an inbound firewall that can prevent unsolicited connections to your Mac.
Little Snitch 3 is $34.95. A demo is available.
See other software choices from Tom's Mac Software Picks.