Download of NetworkKit 9.2.1 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this software for Mac is DoubleREW.net. The program belongs to Internet & Network Tools. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe.
From the developer:
Network Kit comes with a complete set of network tools. You get a complete and easy to understand report of your device's network interfaces. You find information like the IP, IPv6, other addresses or the data usage statistics about your Wi-Fi, Internet or any other network interface. You can monitor your bandwidth with an handy and configurable chart that shows the current download and upload speed.
You may want to check out more software for Mac, such as Covenant Eyes, IPNetRouterX or IPNetTunerX, which might be related to NetworkKit.