what is the best tool available for data driven testing in the server side now?

My process involves processing of lots of data ( a core banking application ) and we cannot depend on a UI because our UI keeps on changing and we are testing mostly on the server side of the application.

So, I would like to know if there is a testing automation tool out there which can do a UI independent, can do server side automation testing( data oriented) and which can have a good integration with CI tool like Teamcity and Bamboo.