HeaderInject

About

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