Header Sets

About

Header Sets lets you define named groups of HTTP headers and activate one
group at a time while you browse. Built for developers who juggle
environments: staging auth tokens, API keys, locale overrides, CORS testing.

★ Sets, not single headers — group the headers that belong together
("Staging auth", "QA locale") and switch with one click
★ Scope each set to specific sites with a URL filter (*.myapp.dev,
localhost, https://api.example.com/v1/*) so tokens never leak elsewhere
★ Request AND response headers — set, append, or remove either direction
(e.g. add Access-Control-Allow-Origin: * for CORS testing)
★ Toggle individual headers on/off to compare behavior
★ Export/import sets as JSON to share configs with your team
★ Toolbar badge shows which set is active; invalid or sensitive header
names are flagged as you type
★ Follows your OS light/dark theme

Built on Chrome's declarativeNetRequest API: headers are applied by the
browser's rule engine, with no JavaScript intercepting your traffic and no
performance overhead.

Privacy: everything stays in your browser. No accounts, no analytics, no
remote servers — see the privacy policy.