Fiddler is a free web debugging tool that works as a proxy, logging all HTTP(S) traffic that is executed by processes in your computer. Fiddler allows you to inspect the traffic to see that exact HTTP request that was sent and the exact HTTP response that was returned. You can also use other advanced features, such as setting breakpoints and overriding the data that is sent or received.

To install Fiddler, navigate to https://www.telerik.com/fiddler and click the Free download button. Save and run the installer:

The Fiddler main screen is built from these main parts:

• Sessions list: Shows the HTTP(S) requests that were sent from processes in your machine
• Fiddler tabs: Contains different tools for inspecting and controlling sessions
• Request inspector: When the Inspectors tab and inner Raw tab are selected, this section shows the request as it was sent over-the-wire
• Response inspector: When the Inspectors tab and inner Raw tab are selected, this section shows the response as it was sent over-the-wire

Immediately after you run Fiddler, it starts collecting the HTTP sessions that are performed in your machine. If you refresh the browser that you used to navigate to the /api/Products API  you created, you should see this session in Fiddler's Sessions List, as shown in the preceding screenshot.

Fiddler is a great tool for debugging the requests and responses that are made in your application, but it means that you need to have a client that sends those requests. Many times when debugging and experimenting with APIs, you want to create HTTP requests manually and inspect them. You can accomplish this task with Fiddler's Composer tab, but I want to teach you about another tool that is much more suitable for these scenarios—Postman.