Multiple instances of Fiddler

3 posts, 1 answers
  1. Denis
    Denis avatar
    2 posts
    Member since:
    May 2014

    Posted 20 Sep 2014 Link to this post


    What is the reason behind prohibition of the running secondary (tertiary, and so on) instance of Fiddler?
    I need to monitor 3 copies of application -- PC app, WP8 app, and OSX app (FiddlerMono is really sucks and hangs, unfortunately).
    It is quite handy to use several copies of Fiddler to avoid the hell of sessions mixing.
    The solution I'm using now -- "run as another user". But it's not quite handy if I run more than 2 copies at once.

    Could you please add an option like "-secondary:port" that will skip a running application check and start Fiddler with different port (which could be indicated at window caption) ?

    Will be glad to any reply!
  2. Answer
    Eric Lawrence
    Eric Lawrence avatar
    832 posts

    Posted 22 Sep 2014 Link to this post

    You can only run one "main" instance of Fiddler because otherwise you run into myriad problems like port contention, proxy chain confusion, settings synchronization, etc, etc.

    However, there are many ways to achieve the goal of isolating traffic even within a single instance; you can use FiddlerScript to render traffic from different clients in different colors, with different icons, etc.

    Alternatively, you can click File > New Viewer to create a new "Viewer" instance of Fiddler. In that new instance, in the QuickExec box below the Web Sessions list, type !listen #### where the number is the port you want to listen on. The Viewer instance will now act as a listening proxy without changing the system's proxy settings or attempting to overwrite any of the settings of the main instance.

    Eric Lawrence

    Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.

  3. Denis
    Denis avatar
    2 posts
    Member since:
    May 2014

    Posted 22 Sep 2014 in reply to Eric Lawrence Link to this post

    Thank you, Eric! Work like a charm.
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