Header Modify

Edit HTTP request & response headers on any site. Profiles, URL filters, and import from ModHeader & Requestly.

Header Modify — edit HTTP request and response headers on any website, no DevTools required. Header Modify is a lightweight extension for adding and managing custom HTTP request and response headers, in the spirit of ModHeader but kept simple and fast. Features • Modify both request and response headers — set, append, or remove • Switch between Request and Response with a simple tab • Header-name autocomplete suggests common keys as you type • Organize headers into multiple profiles — the selected profile is active • Pin any profile with “Always apply” to keep it applied everywhere (📌) • Enable or disable each header with a single toggle • URL filter to apply headers only to the sites you choose • Import your existing setup from ModHeader or Requestly — the format is detected automatically • Export and import your settings as JSON • Available in 52 languages, following your browser language • Privacy-first: everything stays on your device — no accounts, no tracking, no data collection Common uses: send an Authorization / Bearer token, spoof a User-Agent, set an X-Forwarded-For for testing, remove X-Frame-Options or Content-Security-Policy to embed pages, or add CORS headers (Access-Control-Allow-Origin) while developing. Alternative to ModHeader, Requestly, and X-Forwarded-For Header — and you can bring your existing rules with you via import.