AutoResponder Reference

Fiddler's AutoResponder tab allows you to return files from your local disk instead of transmitting the request to the server.

Creating AutoResponder Rules

On the AutoResponder tab, you enter a match string and an action string, and Fiddler will undertake the action if the request URI matches the match string.

You can also Import a .SAZ file to enable playback of previously captured traffic, or drag-drop sessions from the Web Sessions list to replay previous responses. You can also drag-drop files from Windows Explorer to automatically generate AutoResponder Rules for those files.

Keyboard Hints

Hit the Plus key to promote a rule to earlier in the list
Hit the Minus key to demote a rule to later in the list

String Literals

Fiddler will match string literals (case insensitively)

Rule	Matches
*	http://www.example.com/Path1/query=example
EXAMPLE	http://www.example.com/Path1/query=example
path1/	http://www.example.com/Path1/query=example
query	http://www.example.com/Path1/q=Query

Exact Match

Fiddler supports an exact, case-sensitive match syntax for expressions which begin with exact:

Rule	Matches
EXACT:http://www.example.com/path	http://www.example.com/path
EXACT:http://www.example.com/path	http://www.example.com/Path (No Match - mismatched case)
EXACT:http://www.example.com/path	http://www.example.com/path/q=Query (No Match - substring different)

Regular Expressions

Fiddler supports regular expression syntax for expressions which begin with regex:

Rule	Matches
regex:.*	http://www.example.com/Path1/query=example
regex:.*\.jpg	http://www.example.com/Path1/query=foo.jpg&bar http://www.example.com/Path1/query=example.jpg
regex:.*\.jpg$	http://www.example.com/Path1/query=foo.jpg&bar (No Match - improper ending) http://www.example.com/Path1/query=example.jpg
regex:.*\.(jpg\|gif\|bmp)$	http://www.example.com/Path1/query=foo.bmp&bar (No Match - improper ending) http://www.example.com/Path1/query=example.gif http://www.example.com/Path1/query=example.Gif (No Match - mismatched case) http://www.example.com/Path1/query=example.bmp
regex:(?insx).*\.(jpg\|gif\|bmp)$	http://www.example.com/Path1/query=foo.bmp&bar (No Match - improper ending) http://www.example.com/Path1/query=example.gif http://www.example.com/Path1/query=example.Gif http://www.example.com/Path1/query=example.bmp
	Got a great regular expression to share? Please send it to me using the "Contact" link at the top-right side of this page!

You can learn more about regular expressions here.

You can specify regular expression options (like case-sensitivity) by leading the expression with an appropriate declaration. (?insx) works well; it turns on case-insensitivity, requires explicit capture groups, enables single-line syntax, and enables comments after the #character. Learn more on MSDN.

Beyond returning files, you can also perform a few other special actions...

Action String	Result...
filename	Return filename as server's response
*bpu	Break on request before hitting server
*bpafter	Hit server, but break on the response
*drop	Close the client connection immediately without sending a response