Fiddler MCP Server

The Fiddler Everywhere MCP (Model Context Protocol) server lets you interact with LLM models and reach new levels of developer productivity. The MCP server provides proprietary context to AI-powered IDEs, apps, and tools. You can use the Fiddler Everywhere MCP server for comprehensive analysis of captured HTTPS traffic, including web debugging, security highlights, performance reports, data extraction, and general usage. The Fiddler MCP enables you to successfully prompt more complex questions and tasks, and generate tailored code based on the information received from the captured HTTPS traffic.

Prerequisites

To use the Fiddler Everywhere MCP server, you need:

• The latest version of Fiddler Everywhere.
• An active internet connection.
• A unique API Key for the Fiddler Everywhere MCP server (generated within the application).
• A compatible MCP client (IDE, code editor, or app) that supports MCP tools.

Installation

The generic settings for the Fiddler Everywhere MCP server are:

• Server name handle: #fiddler (default value - can be customized through Settings > MCP Server)
• Server type: http
• Server URL: http://localhost:8868/mcp (default value - the port can be customized through Settings > MCP Server)
• Authorization: A generated unique API key to be placed as an Authorization header.

Visual Studio Code

To enable the Fiddler Everywhere MCP server in Visual Studio Code, follow these steps:

1. Start the Fiddler Everywhere application.
2. Go to Settings > MCP Server and complete the following:
   • Set the MCP server port (default value is 8868).
   • Generate a unique API Key.
   • Copy the generated JSON configuration from the VSCode tab.

3. Open your Visual Studio Code workspace and complete the following:

   • Create a .vscode/mcp.json file in your workspace.
   • Paste the copied Fiddler Everywhere MCP configuration. Ensure that the JSON is properly formatted and that the Fiddler MCP server is within the servers property.

   example mcp.json file in VSCode with Fiddler Evereywhere MCP server

   {
       "servers": {
           "fiddler": {
           "type": "http",
           "url": "http://localhost:8868/mcp",
               "headers": {
                   "Authorization": "ApiKey FIDDLER_API_KEY_HERE"
               }
           }
       }
   }
   

4. Start the Fiddler Everywhere MCP server in Visual Studio Code.

Cursor

To enable the Fiddler Everywhere MCP server in Cursor, follow these steps:

1. Start the Fiddler Everywhere application.
2. Go to Settings > MCP Server and complete the following:
   • Set the MCP server port (default value is 8868).
   • Generate a unique API Key.
   • Copy the generated JSON configuration from the Cursor tab.

3. Open your Cursor workspace and complete the following:

   • Create a .cursor/mcp.json file in your workspace.

   • Paste the copied Fiddler Everywhere MCP configuration. Ensure that the JSON is properly formatted and that the Fiddler MCP server is within the mcpServers property.

     example mcp.json file in Cursor with Fiddler Evereywhere MCP server

   {
       "mcpServers": {
           "fiddler": {
           "url": "http://localhost:8868/mcp",
               "headers": {
                   "Authorization": "ApiKey FIDDLER_API_KEY_HERE"
               }
           }
       }
   }
   

4. Start the Fiddler Everywhere MCP server in Cursor.

Usage

To use the Fiddler Everywhere MCP server:

1. Start the Fiddler Everywhere application.
2. Configure the MCP server in your IDE:
   • Visual Studio Code
   • Cursor
   • Or any other compatible IDE that supports MCP servers with tools.
3. Enable the agent mode in your IDE.
4. Start your prompt with #fiddler (or with # followed by your custom server name, if configured).

The MCP server will provide context from your captured HTTPS traffic to enhance your MCP-assisted development workflow.

You can jump start your MCP journey by exploring our prompt library

Supported Capturing Modes

The Fiddler Everywhere MCP server supports the following capturing modes:

• Browser capturing mode
• Terminal capturing mode
• Reverse proxy

MCP Output Sanitization

The Fiddler Everywhere application provides a sanitization tool that automatically removes sensitive data from the output passed to the MCP server. The data sanitization feature enables users to minimize the risk of disclosing specific information.

Even with the feature enabled, Fiddler will attempt to sanitize the captured traffic, but complete removal of sensitive data is not guaranteed. The user is responsible for verifying the output and preventing unintended disclosure.

By default, the sanitization is enabled for all data passing through the MCP server. You can control what type of data to sanitize or add more strict rules through the Settings > Sanitization section.

MCP Access Policies

The Fiddler Everywhere application provides managed application policies through its Fiddler Everywhere Enterprise tier. The DisableMCP policy enables license administrators to completely restrict access to the Fiddler Everywhere MCP server for licensed users.

Windows

IT teams managing Windows systems can apply app configuration keys using their preferred administrative tooling by setting values in the following registry path:

HKEY_CURRENT_USER\SOFTWARE\Policies\Progress\Fiddler Everywhere

Key Name	Description	Value Type	Value Example
DisableMCP	Enables or disables the Fiddler Everywhere MCP server	DWORD-32 (hexadecimal)	1

macOS

IT teams managing macOS systems can apply app configuration using their preferred device management solution (such as Jamf, Intune, or similar) by setting the following keys:

Key Name	Description	Value Type	Value Example
DisableMCP	Enables or disables the Fiddler Everywhere MCP server	integer	1

For more information on using managed application configurations, refer to the Managed Application Policies article.