Another useful tool that is fully integrated with the Selenium WebDriver is called BrowserMob Proxy, and it is developed by Neustar, Inc. This free open source add-on allows users to capture performance data for web applications under test, identify network bottlenecks, modify the behavior of the browser under test, and change traffic patterns on the fly.

Users will set up this proxy server in their Selenium test environment and cast the WebDriver to it, allowing them to manipulate HTTP requests and responses during the test run. It uses the HTTP Archive (HAR) format to capture data.