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Downloading Fiddler for OS X Beta...

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Getting started

  1. If you don’t have the Mono framework installed on your Mac

    Please download it from and install it. If you already have it installed, ensure you’re running the latest version.

  2. If you just installed Mono

    Please open Terminal and type in:

    /Library/Frameworks/Mono.framework/Versions/<Mono Version>/bin/mozroots --import --sync

    (The Mono framework has its own trusted root certificates store. Currently (at mono version 4.2.4) this store remains empty after installing Mono on OS X. Fiddler uses the certificates in this store to validate the certificates of the websites visited. So you need to populate this store with a set of commonly trusted root authorities to avoid getting constant certificate warnings from Fiddler. The mozroots tool imports trusted authorities from the Mozilla LXR. )

  3. Extract to a folder you have write access to.

    It is recommended that the full path to Fiddler install folder does not contain any Windows path illegal characters. (At present it is possible that some Fiddler functionality, e.g. various file exports or Fiddler Script won’t handle such paths.)

  4. Open Terminal and navigate to the folder you extracted to in step 3.


  5. Type mono Fiddler.exe in Terminal.


To further understand the benefits and limitations of Fiddler for OS X please visit this blog post.