The X-Forwarded-For Header is a Firefox extension designed for web developers and IT professionals who need to manage HTTP headers efficiently. This tool enables users to update the X-Forwarded-For header quickly, which is essential for testing purposes in web development. By simply clicking the IP icon or accessing the add-on options, users can easily set their desired IP address.

Once the IP address is configured, all outgoing requests will include the specified X-Forwarded-For header until the user decides to clear it or set it to an empty string. This functionality streamlines the process of testing applications that rely on accurate IP address information, making it a valuable addition to any web development toolkit.