The extension rewrite the headers based on a rules table. It's possible to: add , modify or delete header field for HTTP(S) request or response export the configuration in a file (json format) import the configuration from a file choose urls on which the modifications applies In order to work, the following extension permissions are needed : storage : needed to store the configuration activeTab, tabs : needed to show the configuration screen in the browser tab. webRequest,webRequestBlocking, : needed to modify the headers More information on https://github.com/didierfred/SimpleModifyHeaders The code is opensource under Mozilla Public License 2.0