Intercept an HTTP request at browser end to alter some html content

Question

I would like to do as follows. What would be the best way? A general answer will also be fine.

I would like to intercept an HTTP request at the client end to alter some

Answer 1

You could setup a proxy with HTTPListener. But I would think if you wanted to do it right, you'll need a program that is more low level.

• Open 2 TCP Ports (80 & 443) and actively listen for incoming connections.
• Once received
  • Go out and make the request on behalf of the requester
• Retrieve HTTP Response
• Inspect and change the HTTP Response (where appropriate)
  • Perhaps modifying headers (where appropriate)
• Forward on the response to the requester

I'd start with a simple proxy that just forwards all requests and returns back all responses. Once that is in place you can start inspecting the responses.

That is a good place to start.