Composing requests in Fiddler is easy (just use the ‘Composer’ tab). However, by default, fiddler is set to do ‘GET’ requests – which is what a majority of users seem to be interested in testing. How about if you wanted to test say – a file upload? You would have to work with a POST request – and one that allowed you to upload (send) binary data. How does Fiddler accommodate this?
First, select the POST in the parsed ‘composer’ request window. Now that you are ready to POST, you need your binary data (the file you are trying to upload). Since it will be part of the request body (as opposed to the header), all you need to do is paste the binary contents of the file into the ‘request body’ area. The image below should help clarify these two options.