Is there a tool for Monitoring IP addresses and network activity on MAC OS - similiar to resource monitor on windows 10 On windows 10, there is a program called Resource Monitor. Under the network tab, if I select an application, I can see all the external IP addresses that application is connected to.

Is there something similar to this on MAC OS?

It could be a command line tool or an application.
I recommend Wireshark, if you want detailed information about your network traffic. It works on Windows and MacOS and is even more detailed than Windows Resource Monitor.

If you just want to temporarily monitor the amount of network traffic for a process, the build in MacOS Activity Monitor is sufficient. Though, Activity Monitor does not show which IP each process is connected to and only logs when it is opened.