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ModHead Documentation

Welcome to ModHead - a powerful Chrome extension for modifying HTTP request headers.

What is ModHead?

ModHead is a Chrome extension that allows you to dynamically modify HTTP request headers based on user-defined rules. Whether you're a developer testing APIs, debugging authentication flows, or working with CORS issues, ModHead provides a simple and intuitive interface to manage your HTTP headers.

Key Features

🎯 Dynamic Header Modification

• Add, modify, or remove HTTP request headers on the fly
• Support for all HTTP request types (XHR, Fetch, main frames, sub-frames, scripts, etc.)
• Real-time updates without browser restart

🌐 URL Pattern Matching

• Flexible URL matching with startsWith, endsWith, and equals options
• Multiple target domains per rule
• Optional tab URL filtering for site-specific rules

🔄 Variables System

• Define reusable variables for header values
• Sensitive variable support with password masking
• Use variables across multiple rules with ${variableName} syntax

⚡ Auto-Refresh Tokens

• Automatically refresh authentication tokens
• Support for multiple HTTP methods (GET, POST, PUT, PATCH, DELETE)
• Custom headers and body in refresh requests
• Response transformation to extract specific values (JSON path, templates, or full response)

🎨 User Interface

• Clean, intuitive React-based interface
• Dark theme support
• Enable/disable rules with a single click
• Visual feedback with toast notifications

Documentation Navigation

Getting Started

• Getting Started - Installation and first steps
  • How to install the extension
  • Creating your first rule
  • Understanding URL pattern matching

Core Features

• Variables - Learn about the variables system

  • Creating and managing variables
  • Sensitive variables
  • Using variables in headers

• Auto-Refresh Tokens - Automatic token management

  • Setting up token auto-refresh
  • HTTP methods and configuration
  • Response transformation
  • OAuth and JWT examples

Advanced Usage

• Advanced Features - Power user features

  • Complex response transformations
  • Nested variable usage
  • Multi-stage authentication
  • Tab URL filtering

• Examples - Real-world use cases

  • API key injection
  • Bearer token authentication
  • CORS headers for development
  • OAuth token refresh
  • Multi-stage authentication flows

Help & Support

• FAQ - Frequently asked questions
  • Security considerations
  • Troubleshooting
  • Limitations
  • When rules apply

Quick Example

Here's a simple example of adding an API key to all requests to api.example.com:

1. Create a rule

   • Name: "Example API Key"
   • Target Domain: api.example.com (startsWith)

2. Add a header

   • Name: X-API-Key
   • Value: your-api-key-here

3. Enable the rule and you're done!

All requests to api.example.com/* will now include your API key header.

Architecture Overview

ModHead is built with modern web technologies:

• Manifest V3: Uses Chrome's latest extension architecture
• React: Modern UI with TypeScript
• declarativeNetRequest API: Chrome's powerful API for header modification
• Chrome Storage API: Persistent storage for rules and variables

Contributing

ModHead is an open-source project. Contributions are welcome!

Support

If you encounter issues or have questions:

1. Check the FAQ
2. Review the relevant documentation sections
3. Open an issue on GitHub

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Ready to get started? Head over to the Getting Started Guide!