Roboo uses advanced non-interactive HTTP challenge/response mechanisms to detect and mitigate HTTP robots. Roboo verifies the existence of HTTP, HTML, DOM, Javascript and Flash stacks at the client side. This weeds out the larger percentage of HTTP robots which do not use real browsers or implement full browser stacks, resulting in the mitigation of various web threats such as Flash, HTML and HTML robots. Such deep level of verification weeds out large percentage of. HTTP robots that don’t use real. browsers or use full browsers.
Source: https://thehackernews.com/2011/03/roboo-most-advanced-open-source-http.html