Try LoadUI Pro Free
Part of the ReadyAPI Integrated Suite of API Testing Tools
SoapUI Pro + LoadUI Pro + ServiceV Pro
Ensure your APIs perform everywhere, not just on your own computer. Install load agents on any server, whether on cloud or 'on premise'.
Understand the impacts of your API loads by monitoring your servers, and comparing the results against your performance expectations.
Better utilize the load test results by collecting advanced performance metrics for load test runs. These metrics can be downloaded as intuitive and very interpretable reports.
Get all of the above along with the assurance that the test cases that you created on SoapUI will come in handy when you start performance testing. LoadUI Pro allows you to reuse your SoapUI functional test cases as performance tests.