Key Features

Web Debugging

  • Decrypt and decompress web sessions

    HTTP Compression can dramatically decrease the number of bytes that are transmitted between the server and the client: savings of over 50 percent for HTML, XML, CSS, and JavaScript are common. Using Fiddler’s Transformer tool on the Sessions tab, you can decompress the response or simulate HTTP compression by checking "Simulate GZIP Compression" on the Fiddler Rules menu.

    In addition, Fiddler helps you decrypt HTTPs traffic and display and modify the requests that would otherwise be inscrutable to observers on the network using a man-in-the-middle decryption technique.

  • Analyzing session data

    Fiddler exposes rich functionality to help you analyze web session caching, cookie and header properties in detail. You can easily check if certain pages are missing HTTP Expiration headers that permit client or proxy caching – if a response does not contain Expires or Cache-Control headers, it might not be cached by the client. Additionally, Fiddler offers a reliable way to ensure that the browser is transmitting back the cookies your web site may need.

  • Debug traffic on any system

    You can use Fiddler to debug web traffic from any Windows-based PC, Mac or Linux system, as well as mobile devices like smart phones (iPhone, Windows Phone, Android), and tablet computers. Fiddler is also able to capture traffic from remote computers and network devices that support proxy servers (e.g. tablet computers and phones that support Wi-Fi).

  • Debug traffic from any client and browser

    Fiddler helps you debug traffic from any browser: Internet Explorer, Chrome, Firefox, Safari, Opera, and more. Once you start Fiddler, the web debugger registers itself as the system proxy for Microsoft Windows Internet Services (WinINet), the HTTP layer used by Internet Explorer, Microsoft Office, and many other products. As the system proxy, all HTTP requests from WinINet flow through Fiddler before reaching the target web servers. Similarly, all HTTP responses flow through Fiddler before being returned to the client application.

    Additionally, most devices that support Wi-Fi or Ethernet can be configured to send their traffic to Fiddler; this includes iOS, Android, Windows Phone and Windows RT devices.


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