Header Override is a small browser extension for overriding request headers, response headers, request cookies, and response cookies with configurable local rules.

• Chrome Web Store: https://chromewebstore.google.com/detail/gkobmjeklkiepibofnghbkcjiphjacfm

• Microsoft Edge Add-ons: https://microsoftedge.microsoft.com/addons/detail/albhpnnccbkfkloddpaecdmhpnmnldhn

• Firefox Add-ons: https://addons.mozilla.org/en-US/firefox/addon/headeroverride

• Website: https://headeroverride.com

• Website source: https://github.com/headeroverride/headeroverride.com

extension/      Browser extension source and manifest
tests/          Playwright end-to-end tests
assets/         Store and product assets
docs/           Publishing notes and privacy policy source
scripts/        Release packaging and screenshot helpers
dist/           Ignored local release packages

The public website is maintained in a separate repository so this repository can stay focused on the browser extension.

1. Open your browser's extensions page.
2. Enable Developer mode.
3. Click Load unpacked.
4. Select the extension/ folder.

Open the extension popup, choose a tab, and add a rule:

• Request Headers and Response Headers override HTTP headers for matching URL filters.
• Request Cookies overrides outgoing Cookie headers.
• Response Cookies overrides response Set-Cookie headers.
• URL filter is used for header and cookie rules with declarative request-rule matching syntax. |http* matches HTTP and HTTPS requests.
• Comment is an optional note for labeling or documenting a rule.

Rules are saved automatically and synced into the browser's dynamic request rules.

Install dependencies:

npm ci

Run the end-to-end test suite:

npm run test:e2e

Run tests in headed mode:

npm run test:e2e:headed

Create release packages for Chrome, Edge, and Firefox:

npm run package:extension

Create a package for one browser:

npm run package:extension:chrome
npm run package:extension:edge
npm run package:extension:firefox

Packages are written to the ignored dist/ directory.

Generate screenshots and promotional assets from the real extension UI:

npm run screenshots:generated