arp | rjc arp

{
    "resources": [
        {
            name:       Option<String>,
            address:    String,
            hwtype:     String,
            hwaddress:  String,
            flags_mask: Option<String>,
            iface:      String,
        }
        ...
    ]
}

$ arp | rjc -o=pretty arp
{
    "resources": [
        {
            "name": null,
            "address": "_gateway",
            "hwtype": "ether",
            "hwaddress": "98:9d:5d:e8:0e:4d",
            "flags_mask":"C",
            "iface":"wlp0s20f3"
        }
        ...
    ]
}