Editors' Note: The Download Now link will prompt a local download of the Firefox extension. To install the extension directly, open the file using your Firefox browser.
Modify Headers can modify the user agent string and add headers to spoof a mobile request (e.g. x-up-calling-line-id). Take a look at the help tab of the Modify Headers window. Some people think that 'user-agent' is a custom way of specifying the user agent string.
What's new in this version:
Version 0.7.1.1 has fixed displaying Addon toolbar when a new window is opened.