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

extension/      Browser extension source and manifest
website/        Public website for headeroverride.com
assets/         Generated screenshot output
docs/           Publishing notes and privacy policy source
scripts/        Generated screenshot helper
dist/           Ignored local release packages

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.

The website/ folder contains the public site for headeroverride.com, including the landing page and /privacy route.