Abstract: Techniques and tools relate to analysis of cookies. For example, techniques and tools are described for determining whether cookies stored on a computer in response to a particular event (e.g., the rendering of an advertisement in a browser) are authorized. In one implementation, a cookie analysis system includes a browsing simulator having a web browser and a virtual graphical environment. The browsing simulator renders web pages (e.g., automatically), including ad creative objects (e.g., objects that represent images, graphical animations, video clips, etc.) corresponding to advertisements in the web pages. The cookie analysis system creates test files for the ad creative objects. The cookie analysis system identifies and analyzes cookies (e.g., HTTP cookies, or other objects such as local shared objects) that are set in response to the rendering of ad creative objects.