I’ve been working on several exciting enhancements since I moved to develop Fiddler full-time last month. Major work is underway to improve Fiddler and the Fiddler website, based in part on feedback we’ve received from the poll on the Fiddler homepage.

In today’s post, I’d like to quickly point out a few minor improvements in the current release version that you might have overlooked.

Composer Improvements

Fiddler’s Composer enables you to create and issue a HTTP(S) request, either from scratch, or by dragging in a prior request from the Web Sessions list. The Composer is especially useful for testing REST APIs and doing real-time testing of your web services.

A recent enhancement to the Composer tab is the Scratchpad subtab, which allows you to keep a selection of requests available for quick replay. This can be convenient if you find that there are a small number of requests that you commonly reuse, especially if you find that you need to customize those requests from time-to-time. 

To send a request from the Scratchpad, simply select the text of the request and click the Execute button.


Fiddler will attempt to select an entire request if you triple-click one of the request header lines. To force Fiddler to breakpoint on the request before it is transmitted to the server, hold the SHIFT key while clicking on the Execute button.

Beyond the introduction of the Scratchpad feature, performance of the Composer tab has been enhanced, and it now respects the Font size preference (found inside Tools > Fiddler Options > Appearance).

TextWizard Improvements

Fiddler’s TextWizard permits conversion between the most common forms of encoding used by websites and applications.

While most sites and applications should (and do) use UTF-8 for character-to-byte serialization,  you may occasionally encounter text that was encoded using a different character set.

For instance, say you encounter the sequence %89%EE in a URL. This text is plainly URL-encoded, but if you hit CTRL+E to examine it in the TextWizard, only Unicode-replacement characters are shown:


This is a clue that the text in question wasn’t %-encoded with UTF-8 as the character set.

By clicking the new Encodings… link, you can now inform the TextWizard of what character encodings should be utilized. For instance, by indicating that the Input was actually encoded in the Shift-JIS codepage, the input is decoded into a Japanese character:


Or, if we say that the original text was in the GB2312 codepage, we instead see a Chinese character:


If you’d like to encode text using a non-UTF8 codepage, adjust the Output dropdown accordingly. For example, the Chinese character is encoded as %E5%A4%98 in UTF-8, but if you change the coding to UTF-16, it becomes %18%59:


The TextWizard’s support for alternate character encodings can be helpful when debugging sites that aren’t following the best practice of using UTF-8.

Please stay tuned…

There’s a ton of exciting work on the way for Fiddler, and I can’t wait to share it. Until then, please continue participating in the Fiddler community and sending in bugs and feature requests via Fiddler’s Help > Send Feedback menu.


-Eric Lawrence


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