You can find it from terminal or network utility using netstat scan.
It is not exactly convenient.
You can ping the broadcast address.. so I am using 192.168.2.x ip range.. I ping the address which is used for broadcast.. 255 and it will return results from all the live devices on the network. Although it doesn't tell you what is connected by ethernet and what is connected by wireless.. the ping delay will give you a good idea.. it will continually cycle so press control + c when you are finished.. so as I have shown it starts over again.. The first address with lowest response time is local host.
ping 192.168.2.255
PING 192.168.2.255 (192.168.2.255): 56 data bytes
64 bytes from 192.168.2.204: icmp_seq=0 ttl=64 time=0.082 ms
64 bytes from 192.168.2.201: icmp_seq=0 ttl=255 time=1.144 ms
64 bytes from 192.168.2.126: icmp_seq=0 ttl=255 time=1.472 ms
64 bytes from 192.168.2.203: icmp_seq=0 ttl=255 time=2.071 ms
64 bytes from 192.168.2.35: icmp_seq=0 ttl=64 time=7.164 ms
64 bytes from 192.168.2.204: icmp_seq=1 ttl=64 time=0.191 ms
64 bytes from 192.168.2.201: icmp_seq=1 ttl=255 time=3.657 ms
There are other apps you can get.. one of the best is not computer but iOS.. Fing.
That will work well for most people with iOS device on the lan.