First Steps with Fiddler Everywhere on Windows

This tutorial describes how to install and start using Fiddler Everywhere on Windows.

  • First, you will go through the installation and configuration steps.
  • Next, you'll create a Fiddler account so that you can move on to effectively using the web-debugging tool.
  • Then, you will switch the default Light theme with the Dark one.
  • Finally, you will see how to capture, inspect, and modify traffic.


  • Install Windows 8 x64, Windows 10 x64. or Windows 11 x64.
  • Make sure you have 400MB+ free disk space.
  • Create an account with administrative rights which you'll need for capturing and decoding HTTPS traffic.
  • Provide an active Internet connection with access to the following URLs:
  • Ensure that Fiddler Everywhere's proxy port is open and unrestricted by a firewall/security tool. By default, that's port 8866, but it can be changed from Settings > Connections > Fiddler listens on port.

Step 1: Install Fiddler Everywhere on Your Machine

You'll first have to install the latest version of Fiddler Everywhere on your machine.

  1. Navigate to the Fiddler Everywhere download page.

  2. Select Download for Windows to download the installer.

  3. Run the Fiddler Everywhere exe file to go through the installation process.

Step 2: Create Your Fiddler Account

In this step you'll register by creating your unified Telerik account and become a trial user.

  1. Launch the Fiddler Everywhere application. Follow the Sign in or create an account link.

  2. On the Enter Your Email to Sign in or Create an Account screen, enter the requested information. The email you provide here will be later on used by your collaborators for sharing sessions, collections, and notifications.

  3. Check your inbox and open the confirmation email to complete your account activation.

  4. Return back to the Fiddler Everywhere application and accept the license agreement.

  5. On the next screen, choose whether you want to become a trial user or purchase a subscription plan by selecting either the Start Free Trial or the BUY NOW link. For the purposes of this tutorial, you'll become a trial user by selecting the Start Free Trial option. You are all set to start using the full-scale functionalities Fiddler Everywhere delivers.

Step 3: Style the Tool

Now let's add more elegance to Fiddler Everywhere and change its default Light theme with the Dark one—just go to the Themes menu, select the Dark theme, and click Save. That's it!

Step 4: Capture Secure Traffic

Fiddler Everywhere can capture all HTTP and HTTPS traffic between your computer and the Internet from virtually any application that supports a system proxy.

However, by default, you can only track non-secure HTTP system traffic with Fiddler Everywhere. Therefore, to enable the capturing of HTTPS system traffic, you'll have to install and trust the Fiddler root certificate.

  1. Start Fiddler Everywhere.

  2. Open the Welcome page and click the Enable HTTPS Capture button. Alternatively, follow the link Enable HTTPS now from the inline notification in the Fiddler UI.

    You can also control the trust certificate settings manually. Learn more about the advanced trust certificate options

  3. Click the Trust and Enable HTTPS button.

  4. Confirm the certificate installation in the OS popup.

  5. Back on the main Fiddler Everywhere screen, enable the Live Traffic toggle to start capturing HTTP and HTTPS system traffic.

That's it! Fiddler Everywhere will start immediately to capture all the traffic generated from any application that uses the operating system proxy settings.

Fiddler Everywhere provides the preconfigured browser-capturing option, which enables you to skip the system capturing configuration from this step. The predefined browser-capturing option comes in handy when you generate captured traffic only from a browser, or lack administrative right to install certificates and to modify the system proxy, or when third-party VPNs and security tools are colliding with the Fiddler Everywhere proxy.

Step 5: Fiddle with the Traffic

Let's now continue with capturing and inspecting some HTTPS traffic:

  1. Inspect each session's request and response data through the Inspectors tab.

  2. Extract more details and statistical data by using the Overview tab.

Now you'll extract a captured session:

  1. Go to the Live Traffic tab and select a request/response entry from the sessions list.

  2. Double-click to open the Inspectors tab and inspect the detailed session request/response data.

  3. Switch to the Overview tab to observe technical and statistical data.

Let's modify that session!

  1. Right-click the session of your request to open the context menu of the entry. From there, select Edit in Composer.

  2. When the session opens in a new Composer window, modify its headers. For example, add a new HTTP header with the isTest key and the true value.

  3. Click the tick to add the new HTTP header.

  4. Click the Execute button to replay the modified request.

That was it! Now you are ready to dive more deeply into Fiddler Everywhere and take full advantage of its slick functionalities!

Next Steps