"Telerik Fiddler is a free web debugging proxy for any browser, system or platform".

This tool is very handy when you use a aplication which makes server request and you want to troubleshoot. You can download this tool from here.

After the fiddler is installed launch it, you'll see this window:

How to decrypt HTTPS calls

By default Fiddler doesn't capture https calls.

What does it means?

If the service you want to debug is making the calls using https protocol (secure connection) you'll not be able to see the request.

In order to enable the http capturing go to TOOLS -> OPTIONS -> HTTPS -> check Capture Https and Decript options.

How to use Fiddler

We can split Fiddler's view in 3 parts:

Calls list 

Here you'll all the calls your PC is making to web, including the status code for each call

Request details 

Here you'll see details for the selected service call like: endpoint, headers . If you click on "Raw" tab you can even copy the request and us it elsewhere.

Response details 

Each server "sends information back" this is called server response. The response can contain information in a JSON structure, a raw file and so on.