I've had "Fing" as an app on various tablets for ages, and it's a useful little thing, but I loaded up the desktop version on my PC recently, and the results quite surprised me. Here's the company line:
Fing App is a free network scanner that makes you discover all connected devices, run internet speed tests and help troubleshoot network and device issues. Get Fingbox for more advanced security and protection for your network.
And all of that is pretty much what it does. It also graphically reports internet outages worldwide.
Why I was surprised is because it identified 30 devices on my home network, and they were all mine. The speedtest facility is handy to have to hand rather than using an online version too. It's not one of those incredibly complex pieces of network software but it imparts more than enough knowledge to satisfy the casual-to-intermediate user I'd say.