header-modify-extention

Header Modify

Languages

English (current)：README.md
中文：README.zh_CN.md

Header Modify — rewrite HTTP request headers for the current site

Chrome extension that rewrites request headers for the current site. When enabled, every request from that tab — including iframe / XHR / fetch / media — gets your headers applied with set semantics (add if missing, replace if present).

Built with: chrome-extension-boilerplate-react-vite — a React + Vite 8 Manifest V3 boilerplate with faster builds. This extension is developed on top of that template. Stars and Merge Requests are welcome.

Chrome Web Store

Publishing guide and paste-ready listing copy (5 languages), privacy policy, review justification, and promo images:

STORE.md · STORE.zh-CN.md
docs/chrome-web-store/ — listings, images, checklist
PRIVACY.md · PRIVACY.zh-CN.md

pnpm build
pnpm zip   # → releases/header-modify-extention_v{version}.zip

Regenerate icons / store images:

pnpm assets:store
pnpm build

Preview

Enable for this site — turn rewriting on for the current origin. Rows below are applied with set semantics (add if missing, replace if present).

Popup: Enable for this site is on, with user-agent, x-debug, and accept-language rows

Paste from DevTools — copy headers from Chrome Network (name/value lines, Name: Value, or cURL -H), paste, then Parse & Merge.

Popup: paste DevTools headers and Parse & Merge

Includes iframes — session rules are scoped by tabIds, so the main page, cross-origin iframes, XHR, fetch, and media in that tab all get the same headers.

Diagram: same tab rules apply to main-page and cross-origin iframe requests

Features

Enable rewriting per site (remembered by origin).
Applies to the current tab’s requests, including cross-origin iframes (via declarativeNetRequest session rules + tabIds).
Paste headers copied from Chrome DevTools (alternate name/value lines), Name: Value blocks, or cURL -H flags.
Edit / toggle / delete individual headers in the popup.
Export / import JSON profiles.
UI languages: English, 中文, Español, हिन्दी, العربية.

How it works

Manifest V3 cannot use blocking webRequest. This extension uses:

chrome.declarativeNetRequest.updateSessionRules

with action.type = "modifyHeaders" and operation: "set".

Rules use condition.tabIds for in-tab requests, plus initiatorDomains so Service Worker / Turbo document fetches (no tabId) still match. Header lists and enabled origins persist in chrome.storage.local; session rules are rebuilt when tabs or settings change.

User-Agent: Chrome also sends User-Agent Client Hints (Sec-CH-UA, Sec-CH-UA-Platform, …). Many sites ignore the User-Agent string and use those hints instead. When you set User-Agent, this extension removes those hint headers so the override can take effect.

DevTools: Network may still show the original UA under “Provisional headers are shown”. Check the server (e.g. https://httpbin.org/headers) or a request that is not marked provisional. navigator.userAgent in page JavaScript is not changed by DNR.

Protected headers: Chrome will not SET hop-by-hop / fetch-metadata names such as Host, Content-Length, or Sec-Fetch-*. Those rows are skipped so they do not fail the whole rule (including User-Agent).

Install (development)

pnpm install
pnpm build

Open chrome://extensions/
Enable Developer mode
Click Load unpacked and select the dist/ folder

Dev mode with reload:

pnpm dev

Usage

How it works: open a page, paste headers, enable for this site, reload and inspect Network

Open a normal http(s) page.
Click the extension icon.
Paste DevTools request headers (or add them manually).
Turn on Enable for this site.
Reload the page and inspect Network — requests should show your headers.

DevTools paste example

sec-fetch-user
?1
upgrade-insecure-requests
1
user-agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0.0.0 Safari/537.36

Permissions

Permission	Why
`storage`	Persist headers, enabled origins, language
`tabs`	Resolve the active tab / origin and keep rules in sync
`declarativeNetRequest`	Apply header modifications
`declarativeNetRequestFeedback`	Optional feedback APIs for rule diagnostics
`<all_urls>` host permission	Required to modify headers on page / iframe requests

Scripts

Command	Description
`pnpm dev`	Watch build + HMR helpers
`pnpm build`	Typecheck + production build → `dist/`
`pnpm test`	Vitest (watch)
`pnpm test:run`	Vitest once
`pnpm lint`	ESLint
`pnpm zip`	Pack `dist/` → `releases/header-modify-extention_v*.zip`
`pnpm build:zip`	Production build + zip
`pnpm release:github:dry`	Build zip + preview GitHub Release notes (no tag/push)
`pnpm release:github:full`	Build, commit, tag, `gh release create`, push
`pnpm assets:store`	Regenerate icons + store promo/screenshots

Changelog

Version	Notes
v1.0.0	Initial open-source release: popup editor, DevTools paste, per-site enable, DNR tab-scoped rewrite

License

MIT

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