Header Tool

Header Tool is a small, honest tool for developers and QA engineers who need to change HTTP headers or redirect URLs while testing. What you can do - Set or remove request headers (Authorization, X-Debug, User-Agent, custom headers). - Set or remove response headers (CORS, Cache-Control, CSP experiments). - Redirect URLs using a simple URL pattern or a regular expression with capture groups. - Limit each rule by URL and by resource type (page, XHR/fetch, script, image, and so on). - Group rules into profiles and switch between them. One global switch pauses everything. - See at a glance how many rules are active from the toolbar badge. - Export and import profiles as JSON. Unlimited rules and profiles. Built for trust - No analytics, no telemetry, no ads, no remote code, no accounts. - Rules are stored on your device only. - Uses Chrome's declarativeNetRequest API: the browser applies your rules, the extension never reads your pages or your traffic. - Asks for site access only when you add a rule. Allowing all sites is recommended, because Chrome needs access to both the requested URL and the page making the request; you can instead allow only the sites your rules target (requests made from other sites may not be modified). Decline and nothing runs. - The extension makes no network calls at all. Free, with no limits imposed by the extension. If it saves you time, an optional "Support development" link is available in the popup and options page; donations are voluntary and unlock nothing. Header Tool is an independent project and is not affiliated with any other header-modification extension.