prosdevlab

Auth Header Injector

stable
Updated 1/3/2026

Chrome extension for injecting authentication headers into requests. Built with SDK Kit, React 19, and Manifest V3.

Documentation
Built on
SDK Kit

Overview

Auth Header Injector is a Chrome extension that automatically injects authentication headers into HTTP requests matching your URL patterns. Perfect for developers working with APIs that require bearer tokens or other authorization headers.

Built with SDK Kit for a plugin-based architecture, React 19 for the UI, and Chrome's Manifest V3 APIs.

Features

  • Pattern-based URL matching - Use wildcards to target specific APIs
  • Bearer token injection - Automatically adds Authorization: Bearer {token} headers
  • Side panel UI - Modern React interface with shadcn/ui components
  • Real-time statistics - Track which requests are being intercepted
  • Secure storage - Tokens encrypted in Chrome's sync storage
  • Rule management - Enable/disable rules without deleting them
  • Request tracking - Monitor API calls with detailed stats

Installation

Install from the Chrome Web Store:

# Or load unpacked from source
git clone https://github.com/prosdevlab/auth-header-injector
cd auth-header-injector
pnpm install
pnpm build
# Load dist/ folder in chrome://extensions

Quick Start

  1. Open the side panel - Click the extension icon or use keyboard shortcut
  2. Add a rule - Enter URL pattern (e.g., *://api.example.com/*)
  3. Add token - Paste your bearer token (without "Bearer " prefix)
  4. Enable the rule - Toggle to activate
  5. Browse - Headers are automatically injected into matching requests

URL Pattern Examples

*://api.example.com/*              # Match all API endpoints
*://*/api/v1/*                     # Match /api/v1/ on any domain
*example.com*                      # Match domain anywhere in URL
*://api.staging.example.com/users  # Match specific endpoint

Architecture

Tech Stack

  • Manifest V3 - Latest Chrome extension API
  • React 19 - UI framework
  • Shadcn UI - Component library (Radix UI + Tailwind)
  • SDK Kit - Plugin architecture for service worker
  • Vite - Build tool with watch mode
  • TypeScript - Type safety
  • Vitest - Unit testing

Key Components

  • Service Worker - Background script with SDK Kit plugins
    • chromeStorage - Persistent storage plugin
    • patternMatcher - URL pattern matching
    • requestInterceptor - Header injection via declarativeNetRequest
  • Side Panel UI - React app with real-time stats
  • Request Tracker - Monitors and counts intercepted requests

Performance

  • ✅ Rule caching - In-memory lookup (~0ms)
  • ✅ Batched writes - Stats written every 3s (reduces I/O by ~90%)
  • ✅ Request debouncing - Duplicates ignored for 1s
  • ✅ Event-driven updates - No polling, uses chrome.storage.onChanged

Security & Privacy

  • Local-only storage - All data stored on your device
  • No external servers - Zero network requests to third parties
  • No analytics - We don't collect any usage data
  • Open source - Full transparency for security audits
  • Encrypted sync - Tokens secured in Chrome's sync storage

Development

# Install dependencies
pnpm install
 
# Start dev server (watch mode)
pnpm dev
 
# Build for production
pnpm build
 
# Run tests
pnpm test
 
# Lint & format
pnpm lint
pnpm format

Links

License

MIT License - Free & Open Source

Built for developers who live in the browser 🚀