shoal

Shoal finds the devices on the network segment you are plugged into and fills in what they are, live: a typical /24 is swept in about seven seconds.
Its defining feature is that every value on screen says how it was learned — which probe found it, what was sent, what came back, how sure it is and when it expires — so it is as much a way to learn how a network is discovered as a way to list what is on one. ARP, DNS, mDNS/Bonjour, NetBIOS and ICMP each know a different part of the picture, and you can watch each one answer as it runs.