This is just a quick note to let you know about a feature that recently landed in Proxy.app. The short story is that in the upcoming version you will not only be able to preview the response in an actual browser (unlike the poor html rendering imitations you get with Java-based proxies) but also you will be able to fully introspect the response in the built-in Safari web debugger.
This opens quite a few interesting use-cases. For example, in the past you would typically go through the responses gathered by the proxy without paying much attention on how individual pages are constructed and what is the relationship between the different requests. Once the response is recorded this information is lost. However, with the introduction of the WebView and the debugger we can recover the actual application state at the time of the recording. We can take this concept even further by swapping access to resources which were recorded by the proxy before or after the request was made.
It is early days to say how this will shape in the future, however it is fair to say that it is certainly pushing the boundaries of what is possible today. We are currently awaiting approval from Apple. Once the version is through we will make this feature available to everyone.