Monitoring network usage of individual applications?

I want to monitor each application's network/internet usage on my Mac.

Sort of like how Activity Indicator shows total upload/download usage -- but I also want to know particular application usages.

Is this possible?


The app Little Snitch can do this. Among many other things, it shows traffic by app.

It costs $29, but there is a free trial available.


Another app I've used is RubbertNet (site is down, linked via archive.org). Also not free, but has a free trial available.