HeaderForge

Modify HTTP request and response headers. Rules apply instantly, filter by URL, everything stays in local storage.

HeaderForge is a fast, no-nonsense tool for modifying HTTP request and response headers right in your browser. Set, append, or remove any header on the sites you choose — no proxy, no server changes, no code. Built for developers, QA engineers, and anyone who needs to see how a site behaves under different headers. WHAT YOU CAN DO Request & response headers — set, append, or remove, in both directions Request cookies — add to the outgoing header, or write a real cookie into the browser jar for a whole domain URL filters — scope any rule to the exact hosts and paths you want, with wildcards or full regex Profiles — save entire setups (headers, cookies, filters) and switch between them in one click Import / export — back up your configuration or share it with a teammate Comments — jot a note on any rule so you remember why it exists Verify — confirm the real, post-modification response headers a page actually receives (the DevTools Network panel can't show this) WHY INSTALL IT Your data never leaves your machine. HeaderForge has no server, no analytics, and no telemetry — every rule and profile lives in your browser's local storage, and it's deleted when you remove the extension. No ads. No tracking. No remote code. Just the tool. Free to use and open under the MIT license. No account, no sign-up, no paywall. Rules apply the moment you save them, and a badge shows how many are active at a glance. Works anywhere Chrome runs — macOS, Windows, Linux, and ChromeOS.