Map Local (like Charles Proxy) using Open Source

Question

Is there a way to use Wireshark or some other freeware to get an outcome like one gets when using Charles' Map Local capability?

The way it works in Charles is that you can specify a set of files/folders which are replaced with files from your local disk, anytime your browser requests the specified file(s).

This is super handy for working on complex websites with barriers to getting your changes into source-control, or where you are not allowed to push files onto a staging server during development.

Answer 1

Since asking this question, I have found out that you can do this with Fiddler. This is not strictly an answer, I was asking for something Open Source, and AFAIK Fiddler is not open source.

I'm still holding out for some other easy way to do this, but for now this seems to be the answser. No.