Header Modifier

Add or override HTTP request headers per site, with on/off toggles. Asks for site access one domain at a time.

Header Modifier adds or overrides request headers on traffic your browser sends, using rules you define. HOW IT WORKS Create a rule with a header name, a value, and a URL pattern - for example X-Custom-Header: my-value on *://*.example.com/*. Every matching request the browser makes carries that header. FEATURES • Per-rule on/off toggles, plus a master switch that disables everything without deleting your rules • URL patterns use declarativeNetRequest urlFilter syntax (* is the wildcard) • Rules sync across your signed-in Chrome profiles • Header values are validated, including rejection of CRLF injection • No build step, no dependencies, no external servers LIMITS • Affects requests made by this browser only; server-to-server calls are untouched • Request headers only — response headers are not modified • Some headers cannot be set by extensions; Chrome silently drops those edits