Using Client Certificates

Updated on Nov 6, 2025

To specify the .CER file for Fiddler Classic to return for a given session, add this FiddlerScript*:

c#
oSession["https-Client-Certificate"] = "C:\\test\\someCert.cer";

To specify a .CER file for Fiddler Classic to return otherwise, place that .CER file in:

bash
%USERPROFILE%\My Documents\Fiddler2\ClientCertificate.cer

To generate a .CER file:

  1. Install the certificate in the Current User's Personal Certificate Store.
  2. Right-click the certificate in Personal Certificates Store.
  3. Click All Tasks > Export....
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