Header Modify

Open-source tool to edit HTTP request headers per site, including iframe requests. Paste from Chrome DevTools.

Header Modify is an open-source Chrome extension that rewrites HTTP request headers for websites you enable. OPEN SOURCE Fully open source on GitHub — read the code, audit permissions, file issues, and contribute: https://github.com/webLiang/header-modify-extention No obfuscation, no remote code, no ads. What you install matches the public repository. SINGLE PURPOSE This extension does one thing: on origins you enable, it applies your header overrides to network requests from that tab (including iframes) using Manifest V3 declarativeNetRequest modifyHeaders with set semantics (add if missing, replace if present). WHO IT IS FOR • Front-end developers debugging auth, CORS, locale, or CDN edge cases • QA engineers reproducing client header conditions • Power users who need temporary User-Agent / custom header overrides HOW TO USE 1. After install, rewriting is OFF for every site by default. 2. Open a normal http(s) page, click the toolbar icon, and paste headers copied from Chrome DevTools (or add them manually). 3. Turn on “Enable for this site”. Reload the page and inspect Network — requests should show your headers. 4. Cross-origin iframe requests in the same tab are included (session rules use tabIds). PERMISSIONS • storage — save headers, enabled origins, and language preference locally (never uploaded) • tabs — read the active tab URL/origin so rules stay in sync • declarativeNetRequest — apply header modifications • declarativeNetRequestFeedback — optional rule diagnostics / badge support • host access (<all_urls>) — required to modify headers on arbitrary sites and iframe requests you enable PRIVACY No personal data, browsing history, or page content is collected or sent to any server. Settings stay in chrome.storage.local on your device. See the Privacy Policy linked on this listing. NOT FOR Bypassing paywalls, DRM, account gates, or any unlawful use. This tool only rewrites request headers you configure for legitimate debugging and testing. SOURCE & SUPPORT GitHub: https://github.com/webLiang/header-modify-extention Issues: https://github.com/webLiang/header-modify-extention/issues