The best Network Monitor alternative to Little Snitch is Portmaster, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to Little Snitch and 18 are Network Monitors so hopefully you can find a suitable replacement. Other interesting Network Monitor alternatives to Little Snitch are LuLu by Objective-See, GlassWire, NetLimiter and OpenSnitch.
Little Snitch alternatives are mainly Network Monitors, but if you're looking for
Firewalls or Privacy Tools you can filter on that. Other popular filters include
Windows,
Mac,
Free and
Linux. These are just examples - use the filter bar below to find more specific alternatives to Little Snitch.
I Wanted a tool to replace Little Snitch, and this one is GREAT. It is Free, Open Source, and very lite weight.