HeaderInject

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

HeaderInject is built for testing, development, and authentication workflows that need precise header control. HeaderInject - Custom Headers Made Simple Add, edit, and manage 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 auth headers - 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. Categories: Developer Tools, Productivity Tags: headers, http, api, devtools, testing, authentication, request, debugging