GitHub User: dip00dip
There is SOAPClient. It's very simple - not a near SoapUI in terms of features.
But it might be a plus for simple queries and testing. Was a god bless for me for some time. But as you go deeper there is no alternative SoapUI which is really a pain to use on Mac.
And also there is SimpleWS lib: https://github.com/mikisvaz/simplews
Which is actually a wrap around Soap4r but much easier to get started.