How and with what to replace the json response?

Question

API

There is a request to the API of one resource, in response it receives a json file with a bunch of data, you need to add one parameter. How can you check this scam?
Tried through Fiddler, but it only replaces outgoing ones.

Answer 1

Most likely you want to carry out the so-called MITM attack. Ways may be enough to implement. The simplest is to proxy requests through yourself.