Is there an HTTP proxy tool that can substitute browsed content?

Question

What I'm looking for is some sort of a proxy tool that will allow me to specify a local file to load instead of one specified in the web page that is being browsed. I have tried Burp Suite which is almost working - it allows us to intercept a file and replace it by pasting the contents of the file we are swapping in into an input field. The file content is compiled code (Flash content) so we are pasting in bytecode, but something isn't working.

The reason is we are a 3rd party software developer without access to our client's development or testing environments. Our content must interact correctly with the rest of the content on their webpage (there are elements on their page that communicate with our content) and to test any changes we make takes several hours turnaround to get our files uploaded to their servers. So what we need is some sort of hacking tool to let us test our work with their web pages, hence the requirement to specify a file in a webpage to swap with a local version.

Answer 1

You might be able to do this with Greasemonkey but I'm not sure if the tests will be totally reliable. http://diveintogreasemonkey.org/patterns/replace-element.html

And if Greasemonkey seems plain wrong for you I would take it as the perfect excuse to try out mouseHole. Now I have to admit that I've never tried it but since _why also made Hpricot I expect it to be fun, productive, and different.

Answer 2

I've been using HTTP::Proxy for a long time, and it has always helped me fiddle with things on the fly.

Answer 3

The autoresponder feature in Fiddler Web Debugging Proxy might do what you need, if it's only static content.