Headr - Modify HTTP Headers

Modify HTTP request & response headers. Add, edit or remove headers per site with profiles, filters and presets. 100% local.

Headr is a fast, private HTTP header editor for Chrome. Modify request headers and response headers on any website: add a header, change a header value, or remove a header, then switch it all off with one click. WHAT YOU CAN DO • Modify request headers: Authorization, User-Agent, Accept-Language, X-Forwarded-For, Cookie, custom X- headers • Modify response headers: CORS (Access-Control-Allow-Origin), Content-Security-Policy, Cache-Control • Set, append or remove any header • Profiles: separate header sets for local, dev, staging and production, switched in one click • URL filters: apply a header to one site, a URL pattern or a regular expression, and limit it by resource type • Presets: user agent switcher, CORS testing, cache bypass, CSP testing, forwarded IP and more • Request activity: optional log showing which header rules matched each request (credentials are redacted) • Copy as cURL, import/export JSON, keyboard shortcuts (Alt+H on/off, Alt+N new header) • Dark, light and system themes WHO IT'S FOR Web developers, QA testers, API developers and security testers who need to change HTTP headers to debug APIs, test authentication, check CORS, emulate devices or test how an app handles different headers. PRIVATE BY DESIGN No account. No analytics. No tracking. No ads. Your header rules are stored only in your browser and never leave your device. Headr includes header test patterns (such as injection and host-header values) for testing applications you own or are authorised to test. It is a header-testing tool, not a vulnerability scanner. FREE, WITH A VOICE Headr is free. Use "Feedback & ideas" in the app to suggest features or report bugs. Every message is read.