Mock Traffic

A typical scenario is when a client, a colleague, or a third party is experiencing a specific issue when loading a web application. The problem is often related to the third-party tools (e.g., specific browser version, added extensions) or a set of specific steps that the user undertakes to result in the observed behavior. With Fiddler Everywhere, the user can easily capture and share the sessions with you for further investigation. Going one step further, Fiddler Everywhere allows you to easily mock multiple sessions just as they appeared originally.

Creating and Using a "Mock Traffic" Rule

Fiddler can mock HTTPS traffic captured locally or remotely, for example, as traffic captured by another instance of Fiddler Everywhere and shared as a cloud session or SAZ archive. The following steps showcase how to use a SAZ archive to load and mock the captured traffic (in this case, as loaded from https://example.com)).

  1. Load the SAZ archive with the captured session snapshot. For demonstration purposes, the SAZ will contain traffic as captured from https://example.com).

    Loading SAZ archive with captured traffic

  2. Select all sessions (Ctrl + A on Windows or CMD + A on macOS).

  3. Right-click to invoke the context menu and choose Add New Rules. At this point, Fiddler will automatically generate rules for each captured session and create a parent group. The group's name will be "Selection Import" followed by a timestamp.

    Loading SAZ archive with captured traffic

  4. Switch the Fiddler's tabs from the saved session snapshot to the Live Traffic tab.

  5. Ensure that the switches for the newly created rule group and the Rules tab are toggled ON (refer to the screenshot below). Note that the switches are available only when the Live Traffic tab is focused.

    Loading SAZ archive with captured traffic

The next step is to use one of Fiddler's capturing modes and initiate the traffic capturing (the rules will work only for traffic that goes through the Fiddler proxy). For Example:

  1. Use the Browser to start the browser captruing mode.

  2. Load the URL used by the client to generate the captured sessions (in our case, that would be https://example.com))

That's it! At this very moment, the shown page is not the original one, but the one as mocked from the active Fiddler rules.

Additional Resources