HeaderInject

Inject custom HTTP headers into requests before interacting with web pages. Perfect for testing, development, and authentication.

HeaderInject - Custom Headers Made Simple Add, edit, and manage http request headers from a clean popup UI, then apply them instantly to matching sites. Key Features: - One-click enable/disable toggle - URL pattern targeting (leave blank to apply everywhere) - Add, edit, and delete multiple headers - Prevents duplicate header names - Save and apply changes in one action - Works across most request types (pages, XHR, fetch, media, etc.) - Local-only settings stored in the browser How It Works: 1. Open the extension popup 2. (Optional) Enter a URL pattern like ://api.example.com/ 3. Add one or more headers (name + value) 4. Click "Save & Apply" 5. Reload the page so the rules take effect Perfect For: - Testing APIs that require custom authentication headers or flags - Debugging staging environments with feature flags - Injecting tenant, locale, or environment headers - Quickly switching between header sets during development Privacy First: - No servers involved - Settings are stored locally - No data collection Tips: If a header does not appear, the browser may restrict certain headers from being modified. Reload the page after saving to ensure changes apply.