Modify Header Value (HTTP Headers)

Modify Header Value (HTTP Headers) is an extension that can add, modify or remove an HTTP-request-header for all requests on a desired website or URL. This Addon is very useful if you are an App developer, website designer, or if you want to test a particular header for a request on a website.

Key features:
1. Easily add, modify or remove a header for any request on desired domains.
2. For a complete list of HTTP headers, please take a look at the list of all HTTP Header Fields in the Wikipedia page (

3. Clicking on the Toolbar icon opens a UI to quickly switch the Addon ON or OFF, or open the options page.
4. Each header item has several options to adjust (see add-on's Options page for details)
5. You can add several header items and active or inactive them separately.
6. An example in the options page shows a tutorial on "How to add a custom header".

Note: in order to submit bugs, please visit add-on's homepage (

 and fill the bug report form.