HeaderForge: Modify HTTP Headers

Modify HTTP request and response headers with simple rules. Target any site. Local-only: no tracking, no telemetry.

HeaderForge is a clean, privacy-first HTTP header modifier for developers, QA engineers, and anyone who tests the web. CREATE RULES IN SECONDS - Set, append, or remove any HTTP header - Target all sites or only the domains you choose - Toggle rules on and off instantly - no reload needed BUILT FOR REAL WORKFLOWS - Test auth tokens, feature flags, and A/B variants - Simulate User-Agent, Referer, Accept-Language, and custom headers - Debug CORS, caching, and API behavior - Import/export rule sets as JSON to share with your team (Pro) PRIVACY IS THE PRODUCT - 100% local: rules are stored in your browser and never transmitted - No analytics, no tracking, no ads, no remote code - The only network request we ever make is a one-time license check if you choose to buy Pro - nothing else, ever - Full policy: https://sapirsoftware.github.io/headerforge-privacy.html FREE vs PRO Free: up to 3 active rules, request headers, everything local. Pro (subscription): unlimited rules, response-header modification, JSON import/export. HeaderForge is built by Sapir Software - small tools, done right, with nothing to hide.