This program is exactly what its name suggests: a utility that monitors your network. With its help, you can learn detailed information regarding your current network traffic, IP address, the name of the network you're connected to, maximum speed, etc.
Unlike the network tool that's being integrated in Mac's Activity Monitor, this program actually displays real-time download and upload speed information. Activity Monitor updates the given details at a certain interval of time.
The application lives on your Menu Bar from where you can change the view mode and get direct access to other programs created by the same developer. The utility lets you choose between a medium-sized window showing a graph that's automatically updated and offers you detailed network details, a mini-screen displaying the download and upload speed, and a view mode that puts your current download speed on your Menu Bar. The first two display modes give you the ability to move the app's window anywhere on your desktop.
My only issue with this program is that it doesn't allow you to check tracking history. To be more exact, you cannot check your download or upload speed from 20 minutes ago.
Other than that, nothing bad can be said about this utility. It does exactly what's being said on its homepage, without slowing down your Mac. Plus, it's free.