Everything that you can think of in the test automation world

Here is a mindmap created using github and other resources that gives you test automation tools in every possible technology and phase in product lifecycle:



SoapUI documentation for web services /API testing

General API testing guide is useful for background reading:

A useful resource for learning against a dummy REST API to try your SOAPUI testcases on, either to play with on their server or install it yourself and mimic your api.