A simulator running on a single computer may be configured to appear as multiple users simultaneously initiating Internet requests from separate user environments. An engine of the simulator may communicate with a browser to appear as multiple users each having access to a local defined user account or profile in a computer environment. The simulator may be configured to maintain different user profile data for each user appearing to operate within a separate user environment. The simulator may be configured to simulate a user logged into a particular desktop environment that initiates a browser session and then initiates Internet requests via the browser. The simulator may also simulate at the same time a different user in a different user environment initiating a browser session and initiating Internet requests via the browser. The simulator may be configured to appear as multiple, separate users initiating Internet requests from multiple, different user environments.