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Debug Web API Using Fiddler

In this article, we will see how to debug web API using fiddler.

Software Requirement

Here I am using Telerik fiddler 4 for debugging web API.

Creating Get And Post Method

First of all create a couple of methods i.e. one get method and another post method.

public string Get()
{
    return "value";
}

[HttpPost]
public void Post()
{
            
}

In the preceding code, I have written 2 methods

Get method is returning a hard coded value ‘value’.
Post method does not have anything inside it.

Open Fiddler

Follow these steps to debug the application

Run the application using visual studio and run fiddler.
Go to Composer tab (See the following figure)

Picture showing the Composer tab where service URL and verb can be defined

Click to Enlarge

Select the ‘Get’ verb and enter the URL.
Now click on ‘Execute’ button on the right-hand side (See the following figure)

Picture showing the execute button in the fiddler

Click to Enlarge

And once you click on ‘Execute’, you see that break point on the visual studio will hit.

Picture showing the break point hit for Get method in web API controller

Click to Enlarge

Once the method is debugged (i.e. code inside the method gets executed), go back to Fiddler and check the left-hand side section of Fiddler. You see that the Fiddler has recorded all the calls among client (Web browser) and the server (web API hosted on a development server).

Picture showing the service calls recorded in fiddler

Click to Enlarge

To check the request and response in the preceding figure, click on the record with URL - /api/test.

On the ‘Inspector’ tab you can see the request and response for Get.

Picture showing the request and response header in fiddler

Click to Enlarge

In a similar way, change the Get verb to Post (Put or Delete) to debug respective method.

I hope you like this article. Please share your views.

Posted By -	Karan Gupta

Posted On -	Saturday, January 30, 2016

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