1) This one comes with Visual Studio:
C:Program FilesMicrosoft Visual Studio 9.0Common7IDEWCFTestClient.exe
a) Just add your the URL to your service
b) double clik on the method you want to call
c) fill in the values
d) click invoke
It shows the response formatted, and there is an XML tab to show you the full XML.

2) CodePlex has several:
a) http://wcftestharness.codeplex.com/
b) http://www.codeplex.com/wsdldisco

3) http://www.soapui.org/ – Free and paid version – I think you have to register to get the free version.

If you want to do Load Testing – http://wcfloadtest.codeplex.com/

Neal Walters
March 6, 2009