Configurable Header Manager by Marlon Wiss

Configurable Header Manager lets you intercept and modify HTTP headers on any website — without installing anything beyond the extension itself. HOW IT WORKS Create rules that match a URL pattern (with wildcard support) and define what happens to a header: set a value, remove it entirely, or append to it. Rules apply to request headers (sent to the server) or response headers (received from the server). Toggle individual rules on and off without deleting them. FEATURES • Add, edit and delete header rules per URL pattern • Match any domain or path with wildcard patterns (e.g. ://.example.com/*) • Set, remove or append header values • Works on both request and response headers • Enable or disable rules individually — no need to delete and recreate • Import and export your full rule set as plain JSON — easy backup or team sharing • Load a rule configuration directly from a URL • Instant apply — no page reload of the extension required SIMPLE BY DESIGN The UI is intentionally minimal: a list of your rules, a small form to add or edit one, and an import/export panel. Nothing hidden, nothing complex. SECURE & PRIVACY-FIRST • Zero external dependencies — no npm packages, no remote scripts, no CDN calls • All rules are stored locally in your browser (browser.storage.local) • No analytics, no telemetry, no network requests made by the extension itself • Fully open source — you can read every line of code before installing • Uses the Declarative Net Request API, so the extension never sees the actual request content — the browser engine applies rules directly • data_collection_permissions: none — declared explicitly in the manifest WHO IS THIS FOR Developers testing APIs with custom auth headers, CORS overrides or feature flags; QA engineers spoofing user agents or cache headers; security researchers inspecting header behaviour — anyone who needs precise, per-URL header control without a full proxy setup.